{"content_id":"zmmx3jrpuh","slug":"microwave-container-material-and-safe-use-labels","locale":"en","schema_type":"Article","category":"knowledge_base","category_name":"Knowledge Base","title":"Microwave-Safe Containers: Food-Safe and PP Labels","summary":"Food-safe labels and material names such as PP alone cannot tell you whether a product can be heated. Check whether the product is labeled as suitable for heating, then read the conditions for using the container and lid, along with the permitted temperatures and times.","sponsorship_disclosure":null,"affiliate_disclosure":null,"commerce_disclosure":null,"author":{"name":"Injoys Editorial Team","url":"https://injoys.com/ko/about"},"key_points":["A food-safe label indicates that an item is intended to hold food, not that it is approved for heating.","PP and material identification code 5 describe the material; they do not replace the heating conditions specified for each product.","Check the container and lid separately for microwave suitability and instructions on venting steam.","If the labeling is missing or illegible, check with the manufacturer or transfer the food to a container with clear conditions for use.","Approval to heat single-use packaging does not mean it can be washed and reused repeatedly."],"content_markdown":"Whether a product can go in a microwave depends on its labeling for permitted heating uses. A food-use marking or the material designation PP alone is not enough. The conditions for using the container body and lid must also be checked separately.\n\nThese criteria are based on the Ministry of Food and Drug Safety's guidance dated December 23, 2025, and manufacturers' instructions.\n\n## Differences Between Food-Use, Material, and Heating Labels\n\nDifferent types of markings on containers provide different information. A food-use marking indicates that the product is intended for contact with food. A material marking explains what it is made of. Whether heating is permitted must be checked in separate usage instructions.\n\n| Type of marking | Information provided | What to check separately |\n|---|---|---|\n| Food-use wording or food-utensil symbol | Intended for holding or handling food | Whether heating is permitted |\n| Material designation such as PP | Material used in the product or component | Permitted appliances and conditions |\n| Material identification marking containing a number | Plastic material classification | Whether heating and reuse are permitted |\n| Microwave-use wording or a symbol explained by the manufacturer | Whether that heating method is permitted | Time, temperature, power, and lid handling |\n| Temperature rating | Temperature conditions the product is designed to withstand | Permitted heating methods and duration |\n\nThe MFDS distinguishes between food-use markings and markings permitting heating. The temperature rating of plastic varies with its manufacturing method and material. You must also read the precautions for the specific product before making a decision. [MFDS, “Use Food Utensils Correctly!”](https://www.mfds.go.kr/brd/m_580/view.do?company_cd=\u0026company_nm=\u0026itm_seq_1=0\u0026itm_seq_2=0\u0026multi_itm_seq=0\u0026page=2\u0026seq=160\u0026srchFr=\u0026srchTo=\u0026srchTp=0\u0026srchWord=)\n\n## How to Check Microwave-Use Labels\n\nWording that permits heating must be read alongside the product's conditions of use. The MFDS advises checking product labels even for paper, glass, ceramic, and PP products. Online answers that merely list material names cannot replace this check.\n\nThe MFDS guidance “Know How to Use Microwave-Specific Food Containers!” states:\n\n\u003e Check whether the product is labeled for microwave use and follow the cooking instructions.\n\nThis wording appears in the MFDS guidance dated May 19, 2020. [Original MFDS guidance](https://www.korea.kr/news/cardnewsView.do?newsId=148872536)\n\n1. Check the container and packaging for a food-use marking.\n2. Compare the meaning of any wording or symbol permitting heating with the product instructions.\n3. Check the conditions of use for the container body and lid separately.\n4. Read the permitted power, time, temperature, and intended uses.\n5. Check whether the product is single-use and read any precautions for repeated use.\n\nDo not interpret similar-looking symbols on your own. Dishwasher-safe or freezer-safe markings indicate different conditions of use. If a symbol is not explained, check with the manufacturer.\n\n## What Do PP and the Number 5 Mean?\n\nPP is short for polypropylene, a type of plastic. In the material identification system, the number 5 indicates PP. This number does not indicate a heating time or permitted temperature. [How2Recycle labeling guidelines](https://how2recycle.info/wp-content/uploads/2024/01/How2Recycle_Guidelines_Abbreviated_Feb2024.pdf)\n\nAlthough commonly called a recycling number, its precise function is material identification. ASTM explains that this code does not guarantee actual recyclability. You should therefore not use the number alone to determine whether a product can be recycled or heated. [ASTM D7611/D7611M-21](https://store.astm.org/d7611_d7611m-21.html)\n\nPP products also have different temperature ratings depending on how they are manufactured. Even with the same material, you must check the permitted conditions for each product. The material name is a starting point; the final decision about use depends on the product instructions.\n\n## Deciding How to Use a Product Under Different Conditions\n\nIf only some markings can be confirmed, first obtain the missing information. The table below gives examples of decisions based on both material designations and manufacturers' conditions of use. It does not establish new criteria for permitted uses.\n\n| Confirmed information | Assessment | What to check next |\n|---|---|---|\n| Only a food-use marking is present | Permission to heat has not been confirmed | Heating instructions on the packaging or in the manual |\n| Only PP or the number 5 is present | Only the material has been identified | Permitted uses for that product |\n| The body can be heated, but the lid's suitability is unclear | There is no basis for heating it with the lid | Conditions for removing the lid or using an alternative cover |\n| A microwave-use marking, time, and power are provided | Use under the stated conditions | Instructions on food quantity and lid handling |\n| The markings are worn and unreadable | The product must be identified and checked | Manufacturer, product name, and model information |\n| Single-use packaging has heating instructions | Follow the stated heating method for that food | Whether it can be washed and reused is a separate question |\n\nIf the markings have worn off, purchase records and product photos can help identify the model. It is better to provide the manufacturer with photos of both the body and lid. If suitability cannot be confirmed, transfer the food to another container labeled for heating. The MFDS also advises removing packaging not intended for microwave use and transferring the food to a microwave-specific dish. [MFDS guidance on using plastic containers](https://www.korea.kr/news/policyNewsView.do?newsId=148842779)\n\n## Comparing Conditions of Use for the Body and Lid\n\nEven when the body can be heated, lid handling varies by product. Removing the lid and opening a steam vent are different methods. Do not apply one product's instructions to another airtight container.\n\n| Manufacturer guidance example | Confirmed conditions | Scope of application |\n|---|---|---|\n| LocknLock FAQ for four-sided locking airtight containers | Open all locks and rest the lid at an angle | Products with the structure described in the FAQ |\n| LocknLock FAQ for products with steam vents | Open the steam vent before use | The relevant products with steam vents |\n| IKEA 365+ rectangular plastic 1.0 L product | Can be heated up to 100°C; open the lid during heating to release steam | Product number 392.690.78 |\n\nLocknLock warns that using the product with the locks closed can deform the lid. The same FAQ also advises caution when heating plastic products for extended periods. Heating an empty container can also cause deformation. [LocknLock airtight container FAQ](https://www.locknlock.com/kor/util/customer)\n\nThe **100°C** in the IKEA example is the value specified for that product. It is not a universal temperature for all PP products. Because the guidance has no publication date, check the product page for the latest conditions. (Verified value: microwave heating limit 100°C · Source: ikea.com · Checked 2026-11-01) [IKEA 365+ materials and care instructions](https://www.ikea.com/kr/ko/p/ikea-365-food-container-with-lid-rectangular-plastic-s39269078/)\n\n## Differences Between Reheating, Cooking, and Repeated Use\n\nA marking permitting heating does not automatically permit prolonged cooking or repeated use. The MFDS guidance on plastic containers says to use them for reheating. It also includes a warning against prolonged use for cooking. [MFDS, “Is Microwave-Safe Plastic Safe to Heat?”](https://www.korea.kr/news/policyNewsView.do?newsId=148842779)\n\n| Intended use | Conditions to check | Common source of confusion |\n|---|---|---|\n| Reheating cooked food | Stated power and heating time | Interpreting a microwave-use marking as permission for unlimited heating |\n| Cooking raw ingredients | Containers and cooking methods permitted for cooking | Using a storage container intended for reheating |\n| Defrosting frozen food | Permitted defrosting conditions for the packaging or container | Heating based only on a freezer-safe marking |\n| Reusing delivery containers | Whether they are single-use and the manufacturer's reuse instructions | Relying on a previous heating attempt that seemed fine |\n\nThe distinction between reheating and cooking also matters when making steamed eggs. A container used to reheat cooked food is not necessarily suitable for cooking raw eggs. Check that the container is permitted for cooking and read the appliance's cooking instructions.\n\nHong Kong's Centre for Food Safety advises against reusing containers for convenience meals and takeaway food because they may have been designed for single use. The fact that a container could be heated the first time should not determine whether it can be reused. [Hong Kong Centre for Food Safety, “Microwave Cooking and Food Safety”](https://www.cfs.gov.hk/english/programme/programme_rafs/programme_rafs_ft_01_02_mcfs.html)\n\n## Heat From Food and Container Damage\n\nContainers also become hot through heat transferred from food. Microwaves are absorbed by food, generating heat. The FDA explains that this heat can melt some plastics. Whether microwaves pass through a material is therefore not enough to determine whether it can be used. [FDA, “Microwave Ovens”](https://www.fda.gov/radiation-emitting-products/resources-you-radiation-emitting-products/microwave-ovens)\n\nTake care to avoid burns when removing a container after heating. The MFDS warns against overheating foods high in fat or moisture. Wear gloves or similar protection when removing hot containers. Handle the lid according to the product instructions so that steam can escape.\n\n- Aluminum foil must not be used because it poses a risk of sparks and fire.\n- The MFDS advises against using melamine resin tableware for heating.\n- It advises that PS materials must not be used because they can deform when heated.\n\nThese prohibitions follow the MFDS guidance on food containers. [MFDS precautions by material](https://www.korea.kr/news/cardnewsView.do?newsId=148872536)\n\n## Common Mistakes\n\nThe most common error is using one type of marking to determine all conditions of use. Food use, heat resistance, permission to heat, and repeated use are different kinds of information. Any unconfirmed conditions must be checked in the product instructions or with the manufacturer.\n\n| Common interpretation | Actual information to check |\n|---|---|\n| It is for food use, so it can be heated | Markings permitting each heating method |\n| It is PP, so all products have the same conditions | Product-specific temperature ratings and instructions |\n| The lid comes with the body, so they can be heated together | Separate conditions permitting the lid's use |\n| There is no time limit as long as the temperature rating is not exceeded | Recommended heating time and intended uses |\n| It did not deform last time, so it can keep being used | Whether it is single-use and the conditions for repeated use |\n\nBeing made of glass does not mean a product can be used with every heating method. The MFDS advises following the labeled uses, such as direct-heat or oven use. Glass pots with scratches or cracks must not be used because of the risk of breakage. [MFDS guidance on glass cookware](https://www.mfds.go.kr/brd/m_580/view.do?company_cd=\u0026company_nm=\u0026itm_seq_1=0\u0026itm_seq_2=0\u0026multi_itm_seq=0\u0026page=2\u0026seq=160\u0026srchFr=\u0026srchTo=\u0026srchTp=0\u0026srchWord=)\n\n## Frequently Asked Questions\n\n### Can I heat a product right away if it has a food-use marking?\n\nA food-use marking alone does not tell you whether heating is permitted. You must also check the wording permitting heating and the product-specific conditions of use.\n\n### Is the number 5 a safety rating?\n\nThe number 5 is a material identification number indicating PP. It does not represent a safety ranking or permitted temperature.\n\n### How should I assess a delivery container with no markings?\n\nCheck the packaging instructions with the container manufacturer or food seller. If suitability cannot be confirmed, the rule is to transfer the food to another container labeled for heating.\n\n### Can any container be used if the lid is left slightly open?\n\nFirst check whether the lid itself is permitted for heating. Releasing steam does not remove restrictions on the material's use.\n\n### Is there a heating time that applies to all containers?\n\nThere is no universal time that can be used to decide. Follow the power and time stated on the product.\n\n### Can I wash and reuse a single-use container after heating it once?\n\nA marking permitting heating alone should not be used to decide whether repeated use is allowed. Single-use packaging should not be reused for repeated storage and heating.","content_html":"\u003cp\u003eWhether a product can go in a microwave depends on its labeling for permitted heating uses. A food-use marking or the material designation PP alone is not enough. The conditions for using the container body and lid must also be checked separately.\u003c/p\u003e\n\u003cp\u003eThese criteria are based on the Ministry of Food and Drug Safety's guidance dated December 23, 2025, and manufacturers' instructions.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#differences-between-food-use-material-and-heating-labels\" class=\"anchor\" id=\"differences-between-food-use-material-and-heating-labels\"\u003e\u003c/a\u003eDifferences Between Food-Use, Material, and Heating Labels\u003c/h2\u003e\n\u003cp\u003eDifferent types of markings on containers provide different information. A food-use marking indicates that the product is intended for contact with food. A material marking explains what it is made of. Whether heating is permitted must be checked in separate usage instructions.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eType of marking\u003c/th\u003e\n\u003cth\u003eInformation provided\u003c/th\u003e\n\u003cth\u003eWhat to check separately\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Type of marking\"\u003eFood-use wording or food-utensil symbol\u003c/td\u003e\n\u003ctd data-label=\"Information provided\"\u003eIntended for holding or handling food\u003c/td\u003e\n\u003ctd data-label=\"What to check separately\"\u003eWhether heating is permitted\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Type of marking\"\u003eMaterial designation such as PP\u003c/td\u003e\n\u003ctd data-label=\"Information provided\"\u003eMaterial used in the product or component\u003c/td\u003e\n\u003ctd data-label=\"What to check separately\"\u003ePermitted appliances and conditions\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Type of marking\"\u003eMaterial identification marking containing a number\u003c/td\u003e\n\u003ctd data-label=\"Information provided\"\u003ePlastic material classification\u003c/td\u003e\n\u003ctd data-label=\"What to check separately\"\u003eWhether heating and reuse are permitted\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Type of marking\"\u003eMicrowave-use wording or a symbol explained by the manufacturer\u003c/td\u003e\n\u003ctd data-label=\"Information provided\"\u003eWhether that heating method is permitted\u003c/td\u003e\n\u003ctd data-label=\"What to check separately\"\u003eTime, temperature, power, and lid handling\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Type of marking\"\u003eTemperature rating\u003c/td\u003e\n\u003ctd data-label=\"Information provided\"\u003eTemperature conditions the product is designed to withstand\u003c/td\u003e\n\u003ctd data-label=\"What to check separately\"\u003ePermitted heating methods and duration\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eThe MFDS distinguishes between food-use markings and markings permitting heating. The temperature rating of plastic varies with its manufacturing method and material. You must also read the precautions for the specific product before making a decision. \u003ca href=\"https://www.mfds.go.kr/brd/m_580/view.do?company_cd=\u0026amp;company_nm=\u0026amp;itm_seq_1=0\u0026amp;itm_seq_2=0\u0026amp;multi_itm_seq=0\u0026amp;page=2\u0026amp;seq=160\u0026amp;srchFr=\u0026amp;srchTo=\u0026amp;srchTp=0\u0026amp;srchWord=\"\u003eMFDS, “Use Food Utensils Correctly!”\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#how-to-check-microwave-use-labels\" class=\"anchor\" id=\"how-to-check-microwave-use-labels\"\u003e\u003c/a\u003eHow to Check Microwave-Use Labels\u003c/h2\u003e\n\u003cp\u003eWording that permits heating must be read alongside the product's conditions of use. The MFDS advises checking product labels even for paper, glass, ceramic, and PP products. Online answers that merely list material names cannot replace this check.\u003c/p\u003e\n\u003cp\u003eThe MFDS guidance “Know How to Use Microwave-Specific Food Containers!” states:\u003c/p\u003e\n\u003cblockquote\u003e\n\u003cp\u003eCheck whether the product is labeled for microwave use and follow the cooking instructions.\u003c/p\u003e\n\u003c/blockquote\u003e\n\u003cp\u003eThis wording appears in the MFDS guidance dated May 19, 2020. \u003ca href=\"https://www.korea.kr/news/cardnewsView.do?newsId=148872536\"\u003eOriginal MFDS guidance\u003c/a\u003e\u003c/p\u003e\n\u003col\u003e\n\u003cli\u003eCheck the container and packaging for a food-use marking.\u003c/li\u003e\n\u003cli\u003eCompare the meaning of any wording or symbol permitting heating with the product instructions.\u003c/li\u003e\n\u003cli\u003eCheck the conditions of use for the container body and lid separately.\u003c/li\u003e\n\u003cli\u003eRead the permitted power, time, temperature, and intended uses.\u003c/li\u003e\n\u003cli\u003eCheck whether the product is single-use and read any precautions for repeated use.\u003c/li\u003e\n\u003c/ol\u003e\n\u003cp\u003eDo not interpret similar-looking symbols on your own. Dishwasher-safe or freezer-safe markings indicate different conditions of use. If a symbol is not explained, check with the manufacturer.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#what-do-pp-and-the-number-5-mean\" class=\"anchor\" id=\"what-do-pp-and-the-number-5-mean\"\u003e\u003c/a\u003eWhat Do PP and the Number 5 Mean?\u003c/h2\u003e\n\u003cp\u003ePP is short for polypropylene, a type of plastic. In the material identification system, the number 5 indicates PP. This number does not indicate a heating time or permitted temperature. \u003ca href=\"https://how2recycle.info/wp-content/uploads/2024/01/How2Recycle_Guidelines_Abbreviated_Feb2024.pdf\"\u003eHow2Recycle labeling guidelines\u003c/a\u003e\u003c/p\u003e\n\u003cp\u003eAlthough commonly called a recycling number, its precise function is material identification. ASTM explains that this code does not guarantee actual recyclability. You should therefore not use the number alone to determine whether a product can be recycled or heated. \u003ca href=\"https://store.astm.org/d7611_d7611m-21.html\"\u003eASTM D7611/D7611M-21\u003c/a\u003e\u003c/p\u003e\n\u003cp\u003ePP products also have different temperature ratings depending on how they are manufactured. Even with the same material, you must check the permitted conditions for each product. The material name is a starting point; the final decision about use depends on the product instructions.\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#deciding-how-to-use-a-product-under-different-conditions\" class=\"anchor\" id=\"deciding-how-to-use-a-product-under-different-conditions\"\u003e\u003c/a\u003eDeciding How to Use a Product Under Different Conditions\u003c/h2\u003e\n\u003cp\u003eIf only some markings can be confirmed, first obtain the missing information. The table below gives examples of decisions based on both material designations and manufacturers' conditions of use. It does not establish new criteria for permitted uses.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eConfirmed information\u003c/th\u003e\n\u003cth\u003eAssessment\u003c/th\u003e\n\u003cth\u003eWhat to check next\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Confirmed information\"\u003eOnly a food-use marking is present\u003c/td\u003e\n\u003ctd data-label=\"Assessment\"\u003ePermission to heat has not been confirmed\u003c/td\u003e\n\u003ctd data-label=\"What to check next\"\u003eHeating instructions on the packaging or in the manual\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Confirmed information\"\u003eOnly PP or the number 5 is present\u003c/td\u003e\n\u003ctd data-label=\"Assessment\"\u003eOnly the material has been identified\u003c/td\u003e\n\u003ctd data-label=\"What to check next\"\u003ePermitted uses for that product\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Confirmed information\"\u003eThe body can be heated, but the lid's suitability is unclear\u003c/td\u003e\n\u003ctd data-label=\"Assessment\"\u003eThere is no basis for heating it with the lid\u003c/td\u003e\n\u003ctd data-label=\"What to check next\"\u003eConditions for removing the lid or using an alternative cover\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Confirmed information\"\u003eA microwave-use marking, time, and power are provided\u003c/td\u003e\n\u003ctd data-label=\"Assessment\"\u003eUse under the stated conditions\u003c/td\u003e\n\u003ctd data-label=\"What to check next\"\u003eInstructions on food quantity and lid handling\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Confirmed information\"\u003eThe markings are worn and unreadable\u003c/td\u003e\n\u003ctd data-label=\"Assessment\"\u003eThe product must be identified and checked\u003c/td\u003e\n\u003ctd data-label=\"What to check next\"\u003eManufacturer, product name, and model information\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Confirmed information\"\u003eSingle-use packaging has heating instructions\u003c/td\u003e\n\u003ctd data-label=\"Assessment\"\u003eFollow the stated heating method for that food\u003c/td\u003e\n\u003ctd data-label=\"What to check next\"\u003eWhether it can be washed and reused is a separate question\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eIf the markings have worn off, purchase records and product photos can help identify the model. It is better to provide the manufacturer with photos of both the body and lid. If suitability cannot be confirmed, transfer the food to another container labeled for heating. The MFDS also advises removing packaging not intended for microwave use and transferring the food to a microwave-specific dish. \u003ca href=\"https://www.korea.kr/news/policyNewsView.do?newsId=148842779\"\u003eMFDS guidance on using plastic containers\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#comparing-conditions-of-use-for-the-body-and-lid\" class=\"anchor\" id=\"comparing-conditions-of-use-for-the-body-and-lid\"\u003e\u003c/a\u003eComparing Conditions of Use for the Body and Lid\u003c/h2\u003e\n\u003cp\u003eEven when the body can be heated, lid handling varies by product. Removing the lid and opening a steam vent are different methods. Do not apply one product's instructions to another airtight container.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eManufacturer guidance example\u003c/th\u003e\n\u003cth\u003eConfirmed conditions\u003c/th\u003e\n\u003cth\u003eScope of application\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Manufacturer guidance example\"\u003eLocknLock FAQ for four-sided locking airtight containers\u003c/td\u003e\n\u003ctd data-label=\"Confirmed conditions\"\u003eOpen all locks and rest the lid at an angle\u003c/td\u003e\n\u003ctd data-label=\"Scope of application\"\u003eProducts with the structure described in the FAQ\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Manufacturer guidance example\"\u003eLocknLock FAQ for products with steam vents\u003c/td\u003e\n\u003ctd data-label=\"Confirmed conditions\"\u003eOpen the steam vent before use\u003c/td\u003e\n\u003ctd data-label=\"Scope of application\"\u003eThe relevant products with steam vents\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Manufacturer guidance example\"\u003eIKEA 365+ rectangular plastic 1.0 L product\u003c/td\u003e\n\u003ctd data-label=\"Confirmed conditions\"\u003eCan be heated up to 100°C; open the lid during heating to release steam\u003c/td\u003e\n\u003ctd data-label=\"Scope of application\"\u003eProduct number 392.690.78\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eLocknLock warns that using the product with the locks closed can deform the lid. The same FAQ also advises caution when heating plastic products for extended periods. Heating an empty container can also cause deformation. \u003ca href=\"https://www.locknlock.com/kor/util/customer\"\u003eLocknLock airtight container FAQ\u003c/a\u003e\u003c/p\u003e\n\u003cp\u003eThe \u003cstrong\u003e100°C\u003c/strong\u003e in the IKEA example is the value specified for that product. It is not a universal temperature for all PP products. Because the guidance has no publication date, check the product page for the latest conditions. (Verified value: microwave heating limit 100°C · Source: ikea.com · Checked 2026-11-01) \u003ca href=\"https://www.ikea.com/kr/ko/p/ikea-365-food-container-with-lid-rectangular-plastic-s39269078/\"\u003eIKEA 365+ materials and care instructions\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#differences-between-reheating-cooking-and-repeated-use\" class=\"anchor\" id=\"differences-between-reheating-cooking-and-repeated-use\"\u003e\u003c/a\u003eDifferences Between Reheating, Cooking, and Repeated Use\u003c/h2\u003e\n\u003cp\u003eA marking permitting heating does not automatically permit prolonged cooking or repeated use. The MFDS guidance on plastic containers says to use them for reheating. It also includes a warning against prolonged use for cooking. \u003ca href=\"https://www.korea.kr/news/policyNewsView.do?newsId=148842779\"\u003eMFDS, “Is Microwave-Safe Plastic Safe to Heat?”\u003c/a\u003e\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eIntended use\u003c/th\u003e\n\u003cth\u003eConditions to check\u003c/th\u003e\n\u003cth\u003eCommon source of confusion\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Intended use\"\u003eReheating cooked food\u003c/td\u003e\n\u003ctd data-label=\"Conditions to check\"\u003eStated power and heating time\u003c/td\u003e\n\u003ctd data-label=\"Common source of confusion\"\u003eInterpreting a microwave-use marking as permission for unlimited heating\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Intended use\"\u003eCooking raw ingredients\u003c/td\u003e\n\u003ctd data-label=\"Conditions to check\"\u003eContainers and cooking methods permitted for cooking\u003c/td\u003e\n\u003ctd data-label=\"Common source of confusion\"\u003eUsing a storage container intended for reheating\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Intended use\"\u003eDefrosting frozen food\u003c/td\u003e\n\u003ctd data-label=\"Conditions to check\"\u003ePermitted defrosting conditions for the packaging or container\u003c/td\u003e\n\u003ctd data-label=\"Common source of confusion\"\u003eHeating based only on a freezer-safe marking\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Intended use\"\u003eReusing delivery containers\u003c/td\u003e\n\u003ctd data-label=\"Conditions to check\"\u003eWhether they are single-use and the manufacturer's reuse instructions\u003c/td\u003e\n\u003ctd data-label=\"Common source of confusion\"\u003eRelying on a previous heating attempt that seemed fine\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eThe distinction between reheating and cooking also matters when making steamed eggs. A container used to reheat cooked food is not necessarily suitable for cooking raw eggs. Check that the container is permitted for cooking and read the appliance's cooking instructions.\u003c/p\u003e\n\u003cp\u003eHong Kong's Centre for Food Safety advises against reusing containers for convenience meals and takeaway food because they may have been designed for single use. The fact that a container could be heated the first time should not determine whether it can be reused. \u003ca href=\"https://www.cfs.gov.hk/english/programme/programme_rafs/programme_rafs_ft_01_02_mcfs.html\"\u003eHong Kong Centre for Food Safety, “Microwave Cooking and Food Safety”\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#heat-from-food-and-container-damage\" class=\"anchor\" id=\"heat-from-food-and-container-damage\"\u003e\u003c/a\u003eHeat From Food and Container Damage\u003c/h2\u003e\n\u003cp\u003eContainers also become hot through heat transferred from food. Microwaves are absorbed by food, generating heat. The FDA explains that this heat can melt some plastics. Whether microwaves pass through a material is therefore not enough to determine whether it can be used. \u003ca href=\"https://www.fda.gov/radiation-emitting-products/resources-you-radiation-emitting-products/microwave-ovens\"\u003eFDA, “Microwave Ovens”\u003c/a\u003e\u003c/p\u003e\n\u003cp\u003eTake care to avoid burns when removing a container after heating. The MFDS warns against overheating foods high in fat or moisture. Wear gloves or similar protection when removing hot containers. Handle the lid according to the product instructions so that steam can escape.\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003eAluminum foil must not be used because it poses a risk of sparks and fire.\u003c/li\u003e\n\u003cli\u003eThe MFDS advises against using melamine resin tableware for heating.\u003c/li\u003e\n\u003cli\u003eIt advises that PS materials must not be used because they can deform when heated.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThese prohibitions follow the MFDS guidance on food containers. \u003ca href=\"https://www.korea.kr/news/cardnewsView.do?newsId=148872536\"\u003eMFDS precautions by material\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#common-mistakes\" class=\"anchor\" id=\"common-mistakes\"\u003e\u003c/a\u003eCommon Mistakes\u003c/h2\u003e\n\u003cp\u003eThe most common error is using one type of marking to determine all conditions of use. Food use, heat resistance, permission to heat, and repeated use are different kinds of information. Any unconfirmed conditions must be checked in the product instructions or with the manufacturer.\u003c/p\u003e\n\u003cdiv class=\"overflow-x-auto\"\u003e\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eCommon interpretation\u003c/th\u003e\n\u003cth\u003eActual information to check\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common interpretation\"\u003eIt is for food use, so it can be heated\u003c/td\u003e\n\u003ctd data-label=\"Actual information to check\"\u003eMarkings permitting each heating method\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common interpretation\"\u003eIt is PP, so all products have the same conditions\u003c/td\u003e\n\u003ctd data-label=\"Actual information to check\"\u003eProduct-specific temperature ratings and instructions\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common interpretation\"\u003eThe lid comes with the body, so they can be heated together\u003c/td\u003e\n\u003ctd data-label=\"Actual information to check\"\u003eSeparate conditions permitting the lid's use\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common interpretation\"\u003eThere is no time limit as long as the temperature rating is not exceeded\u003c/td\u003e\n\u003ctd data-label=\"Actual information to check\"\u003eRecommended heating time and intended uses\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd data-label=\"Common interpretation\"\u003eIt did not deform last time, so it can keep being used\u003c/td\u003e\n\u003ctd data-label=\"Actual information to check\"\u003eWhether it is single-use and the conditions for repeated use\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\u003c/div\u003e\n\u003cp\u003eBeing made of glass does not mean a product can be used with every heating method. The MFDS advises following the labeled uses, such as direct-heat or oven use. Glass pots with scratches or cracks must not be used because of the risk of breakage. \u003ca href=\"https://www.mfds.go.kr/brd/m_580/view.do?company_cd=\u0026amp;company_nm=\u0026amp;itm_seq_1=0\u0026amp;itm_seq_2=0\u0026amp;multi_itm_seq=0\u0026amp;page=2\u0026amp;seq=160\u0026amp;srchFr=\u0026amp;srchTo=\u0026amp;srchTp=0\u0026amp;srchWord=\"\u003eMFDS guidance on glass cookware\u003c/a\u003e\u003c/p\u003e\n\u003ch2\u003e\n\u003ca href=\"#frequently-asked-questions\" class=\"anchor\" id=\"frequently-asked-questions\"\u003e\u003c/a\u003eFrequently Asked Questions\u003c/h2\u003e\n\u003ch3\u003e\n\u003ca href=\"#can-i-heat-a-product-right-away-if-it-has-a-food-use-marking\" class=\"anchor\" id=\"can-i-heat-a-product-right-away-if-it-has-a-food-use-marking\"\u003e\u003c/a\u003eCan I heat a product right away if it has a food-use marking?\u003c/h3\u003e\n\u003cp\u003eA food-use marking alone does not tell you whether heating is permitted. You must also check the wording permitting heating and the product-specific conditions of use.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#is-the-number-5-a-safety-rating\" class=\"anchor\" id=\"is-the-number-5-a-safety-rating\"\u003e\u003c/a\u003eIs the number 5 a safety rating?\u003c/h3\u003e\n\u003cp\u003eThe number 5 is a material identification number indicating PP. It does not represent a safety ranking or permitted temperature.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#how-should-i-assess-a-delivery-container-with-no-markings\" class=\"anchor\" id=\"how-should-i-assess-a-delivery-container-with-no-markings\"\u003e\u003c/a\u003eHow should I assess a delivery container with no markings?\u003c/h3\u003e\n\u003cp\u003eCheck the packaging instructions with the container manufacturer or food seller. If suitability cannot be confirmed, the rule is to transfer the food to another container labeled for heating.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#can-any-container-be-used-if-the-lid-is-left-slightly-open\" class=\"anchor\" id=\"can-any-container-be-used-if-the-lid-is-left-slightly-open\"\u003e\u003c/a\u003eCan any container be used if the lid is left slightly open?\u003c/h3\u003e\n\u003cp\u003eFirst check whether the lid itself is permitted for heating. Releasing steam does not remove restrictions on the material's use.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#is-there-a-heating-time-that-applies-to-all-containers\" class=\"anchor\" id=\"is-there-a-heating-time-that-applies-to-all-containers\"\u003e\u003c/a\u003eIs there a heating time that applies to all containers?\u003c/h3\u003e\n\u003cp\u003eThere is no universal time that can be used to decide. Follow the power and time stated on the product.\u003c/p\u003e\n\u003ch3\u003e\n\u003ca href=\"#can-i-wash-and-reuse-a-single-use-container-after-heating-it-once\" class=\"anchor\" id=\"can-i-wash-and-reuse-a-single-use-container-after-heating-it-once\"\u003e\u003c/a\u003eCan I wash and reuse a single-use container after heating it once?\u003c/h3\u003e\n\u003cp\u003eA marking permitting heating alone should not be used to decide whether repeated use is allowed. Single-use packaging should not be reused for repeated storage and heating.\u003c/p\u003e\n","tags":["Kitchenware","Household essentials","Food storage"],"faqs":[{"question":"What is the difference between a food-use label and a label indicating suitability for heating?","answer":"A food-use label indicates that a product is intended for holding or handling food. A label indicating suitability for heating means it can be used with a specific heating method. You also need to check product-specific conditions, such as usage time and temperature."},{"question":"Can a product made of PP be used for heating?","answer":"You cannot judge by the material name PP alone. Even products made of the same material can have different permitted conditions depending on how they are manufactured and their intended use. You need to check the product's label indicating suitability for heating."},{"question":"What does the number 5 on the bottom of a container mean?","answer":"In the material identification system, the number 5 stands for PP, or polypropylene. It does not indicate a permitted heating temperature or a safety rating."},{"question":"If the container body is suitable for heating, can I put the lid in with it?","answer":"You need to check the conditions for the container body and lid separately. Follow the product-specific instructions, such as removing the lid, releasing the locking mechanism, or opening the steam vent."},{"question":"How can I check a container if its label has worn off?","answer":"You can identify the model from purchase records or product photos. Ask the manufacturer about the conditions of use for both the container body and the lid. If you cannot confirm them, use another container labeled as suitable for heating."},{"question":"Can I determine the heating time from the temperature rating alone?","answer":"The temperature rating alone does not determine the permitted heating time. You also need to check the power, time, intended use, and food quantity conditions specified on the product."},{"question":"Can I make steamed eggs in a plastic container intended for reheating?","answer":"A label stating that a container is intended for reheating does not mean that it is also suitable for cooking raw eggs. You need to check that the container is approved for cooking and check the appliance's cooking instructions."},{"question":"Can single-use packaging that is suitable for heating be reused?","answer":"Permission to heat single-use packaging is different from permission to reuse it. The Hong Kong Centre for Food Safety advises against reusing containers for convenience meals and takeaway food."},{"question":"Can all glass containers be used?","answer":"You also need to check the heating uses indicated on glass products. The Ministry of Food and Drug Safety advises against using glass pots with scratches or cracks because of the risk of breakage."}],"sources":[{"url":"https://www.mfds.go.kr/brd/m_580/view.do?company_cd=\u0026company_nm=\u0026itm_seq_1=0\u0026itm_seq_2=0\u0026multi_itm_seq=0\u0026page=2\u0026seq=160\u0026srchFr=\u0026srchTo=\u0026srchTp=0\u0026srchWord=","title":"Ministry of Food and Drug Safety, Use Food-Contact Cooking Utensils Properly!, December 23, 2025","type":"source"},{"url":"https://www.korea.kr/news/cardnewsView.do?newsId=148872536","title":"Ministry of Food and Drug Safety, Microwave-Safe Food Containers: Know the Facts and Use Them Properly!, May 19, 2020","type":"source"},{"url":"https://www.korea.kr/news/policyNewsView.do?newsId=148842779","title":"Ministry of Food and Drug Safety, Plastics for Microwave Use: Are They Safe to Heat?","type":"source"},{"url":"https://store.astm.org/d7611_d7611m-21.html","title":"ASTM D7611/D7611M-21, Standard Practice for Coding Plastic Manufactured Articles for Resin Identification","type":"source"},{"url":"https://how2recycle.info/wp-content/uploads/2024/01/How2Recycle_Guidelines_Abbreviated_Feb2024.pdf","title":"How2Recycle Guidelines, February 2024, Resin Identification Codes","type":"source"},{"url":"https://www.locknlock.com/kor/util/customer","title":"LocknLock Customer Support, FAQ on Using Airtight Containers for Heating","type":"source"},{"url":"https://www.ikea.com/kr/ko/p/ikea-365-food-container-with-lid-rectangular-plastic-s39269078/","title":"IKEA 365+ food storage container+lid, rectangular plastic 1.0 L, product number 392.690.78","type":"data_point"},{"url":"https://www.fda.gov/radiation-emitting-products/resources-you-radiation-emitting-products/microwave-ovens","title":"FDA, Microwave Ovens","type":"source"},{"url":"https://www.cfs.gov.hk/english/programme/programme_rafs/programme_rafs_ft_01_02_mcfs.html","title":"Hong Kong Centre for Food Safety, Microwave Cooking and Food Safety, June 2005","type":"source"}],"images":[{"id":2313,"url":"https://injoys.com/rails/active_storage/blobs/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzU1NzMsInB1ciI6ImJsb2JfaWQifX0=--8a75de6f3de934ec98640d3f394971fd9f941814/ai-d96e3630.webp","is_representative":true,"generation_method":"ai_photo","license":"ai_generated","mime_type":"image/webp","width":1536,"height":1024,"translations":{"ko":{"alt":"열린 전자레인지 옆에서 남성이 플라스틱 용기의 밥과 채소를 유리 그릇으로 옮기고 있다.","caption":"가열 조건이 불분명하면 전자레인지 사용 조건이 확인된 용기로 음식을 옮겨야 한다.","description":null},"en":{"alt":"A man transfers rice and vegetables from a plastic tub to a glass bowl beside an open microwave.","caption":"If heating instructions are unclear, transfer food to a container with confirmed microwave-use conditions.","description":null},"ja":{"alt":"開いた電子レンジの横で、男性がプラスチック容器のご飯と野菜をガラスのボウルに移している。","caption":"加熱条件が不明な場合は、電子レンジでの使用条件が確認できる容器に食品を移す必要がある。","description":null},"es":{"alt":"Un hombre pasa arroz y verduras de un recipiente de plástico a un bol de vidrio junto a un microondas abierto.","caption":"Si las instrucciones de calentamiento no son claras, pasa la comida a un recipiente con uso en microondas confirmado.","description":null},"id":{"alt":"Seorang pria memindahkan nasi dan sayuran dari wadah plastik ke mangkuk kaca di samping microwave terbuka.","caption":"Jika petunjuk pemanasan tidak jelas, pindahkan makanan ke wadah yang ketentuan penggunaan microwavenya sudah dipastikan.","description":null},"pt":{"alt":"Um homem passa arroz e legumes de um recipiente plástico para uma tigela de vidro ao lado de um micro-ondas aberto.","caption":"Se as instruções de aquecimento não forem claras, transfira a comida para um recipiente com uso em micro-ondas confirmado.","description":null},"zh-hant":{"alt":"一名男子在打開的微波爐旁，將塑膠容器裡的米飯和蔬菜移至玻璃碗中。","caption":"加熱條件不明時，應將食物移至已確認微波使用條件的容器中。","description":null},"de":{"alt":"Ein Mann füllt Reis und Gemüse aus einer Plastikdose in eine Glasschüssel neben einer offenen Mikrowelle.","caption":"Bei unklaren Erhitzungshinweisen sollten Speisen in einen Behälter mit bestätigten Mikrowellen-Nutzungsbedingungen umgefüllt werden.","description":null}}},{"id":2314,"url":"https://injoys.com/rails/active_storage/blobs/proxy/eyJfcmFpbHMiOnsiZGF0YSI6MzU1NzksInB1ciI6ImJsb2JfaWQifX0=--d60e6e32f0e8988de407316cf0b5bd8aa2e707bd/ai-ae299700.webp","is_representative":false,"generation_method":"ai_semi","license":"ai_generated","mime_type":"image/webp","width":1536,"height":1024,"translations":{"ko":{"alt":"여성이 양손에 오븐 장갑을 끼고 뚜껑의 증기 배출구가 열린 음식 용기를 전자레인지에서 꺼내고 있다.","caption":"용기 본체와 뚜껑의 전자레인지 사용 가능 여부를 각각 확인하고 증기 배출 지침을 따라야 한다.","description":null},"en":{"alt":"A woman wearing oven mitts removes a steaming food container with its lid vent open from a microwave.","caption":"Check microwave suitability for the container and lid separately, and follow the steam-venting instructions.","description":null},"ja":{"alt":"女性が両手にオーブンミトンを着け、ふたの蒸気口を開けた湯気の立つ食品容器を電子レンジから取り出している。","caption":"容器本体とふたが電子レンジに対応しているかをそれぞれ確認し、蒸気の逃がし方の指示に従う必要がある。","description":null},"es":{"alt":"Una mujer con manoplas saca del microondas un recipiente humeante con la válvula de la tapa abierta.","caption":"Comprueba por separado si el recipiente y la tapa son aptos para microondas y sigue las instrucciones de ventilación.","description":null},"id":{"alt":"Perempuan memakai sarung tangan oven mengeluarkan wadah beruap dari microwave dengan ventilasi tutup terbuka.","caption":"Periksa kelayakan wadah dan tutup untuk microwave secara terpisah, lalu ikuti petunjuk pelepasan uap.","description":null},"pt":{"alt":"Uma mulher com luvas de forno retira do micro-ondas um recipiente fumegante com a válvula da tampa aberta.","caption":"Verifique separadamente se o recipiente e a tampa podem ir ao micro-ondas e siga as instruções de liberação de vapor.","description":null},"zh-hant":{"alt":"一名女子雙手戴著隔熱手套，從微波爐取出冒著蒸氣的食物容器，蓋上的排氣孔處於開啟狀態。","caption":"應分別確認容器本體與蓋子是否適用於微波爐，並遵循蒸氣排放指示。","description":null},"de":{"alt":"Eine Frau nimmt mit Ofenhandschuhen eine dampfende Dose mit offenem Deckelventil aus der Mikrowelle.","caption":"Prüfen Sie die Mikrowelleneignung von Behälter und Deckel getrennt und beachten Sie die Hinweise zum Dampfablass.","description":null}}}],"published_at":"2026-11-01T00:39:19+09:00","updated_at":"2026-11-01T00:39:19+09:00","license":"cc_by","translation_status":"reviewed","available_locales":["ko","en","ja","es"],"data_locales":["ko","en","ja","es","id","pt","zh-hant","de"],"url":"https://injoys.com/en/articles/microwave-container-material-and-safe-use-labels"}