oSIST prEN 18372:2026

• Abstract:

  This document establishes a methodology framework for testing metal-made articles in contact with foodstuffs for use in domestic microwave applicators. An experimental method aiming at qualifying this class of articles is proposed. The objectives of the method are two-folds: ensuring a correct eating efficiency considering a standard microwave heating cycle and guarantying the user safety notably regarding the risk of electrical discharge.

• Status: Not Published
• Public Enquiry End Date: 02-Sep-2026
• ICS: 67.250 - Materials and articles in contact with foodstuffs
• ICS: 97.040.20 - Cooking ranges, working tables, ovens and similar appliances
• Technical Committee: EPO - Packaging - sales and grouped
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 05-Jun-2026
• Due Date: 23-Oct-2026
• Completion Date: 24-Sep-2026
• Ref Project: prEN 18372 - Materials and articles in contact with foodstuffs — Evaluation of the suitability of metal and alloy articles in contact with foodstuffs during microwave heating

oSIST prEN 18372:2026 is a draft European standard from CEN for evaluating metal and alloy containers and articles used with foodstuffs during microwave heating. It specifies a test method for safety, heating performance, marking and the test report for articles intended for domestic microwave ovens, mainly for manufacturers, suppliers and test laboratories.

What does oSIST prEN 18372:2026 specify?

oSIST prEN 18372:2026 specifies how to assess the suitability of metal or partially metal articles, coated or uncoated, when they are used as containers for foodstuffs or drinks during microwave heating. The document focuses on two practical questions: does the article heat food efficiently, and does it stay safe in the oven without causing arcing or damage?

The scope applies to containers designed for microwave use only inside the microwave oven, whether they are single-use or reusable. It excludes microwave combination appliances, microwave ovens with impingement function, and microwave ovens with an input power lower than 900 W. It also excludes models without a protective dielectric barrier that would allow direct metal-to-metal contact with the oven base.

The document is organized into these main clauses:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Terms and definitions
• Clause 4 - Principle
• Clause 5 - Apparatus
• Clause 6 - Test pieces
• Clause 7 - Calibration of the microwave oven: determination of the effective power output
• Clause 8 - Operating procedure
• Clause 9 - Marking, labelling or instructions for use
• Clause 10 - Test report

What are the key requirements of oSIST prEN 18372:2026?

oSIST prEN 18372:2026 sets out a test sequence that begins with oven calibration and ends with a pass-fail judgment on safety, heating performance and consumer information. In practice, the standard tells a laboratory how to prepare the oven, how to load the container, what to watch for during heating, and what information must accompany the product.

Calibration and test set-up

Clause 7 calibrates the microwave oven by heating water in a borosilicate glass beaker and calculating the effective power output from the temperature rise and heating time. This matters because the later heating time for the container is based on the measured power of the actual oven used, not on a nominal value.

Clause 5 requires a microwave oven that can operate with metal containers, a temperature measuring device, a stopwatch, scales, a graduated rule and the specified borosilicate glass beaker. The oven is run at a continuous power setting, and the container must keep at least 25 mm from the cavity walls. That distance is important because it reduces the risk of electrical discharge.

Safety testing

Clause 6 requires new test pieces and a visual check before testing. Containers with impact damage, deformation or other visible defects are not used, and smaller defects such as pitting or corrosion are recorded.

Clause 8.2 places the container in four positions in the cavity and runs the oven for three times the theoretical heating time, up to a maximum of 20 minutes. If an electric arc occurs, the test stops immediately and the article fails the safety requirement. The container also fails if its appearance changes or if it damages the oven cavity.

Heating performance

Clause 8.1 determines the theoretical heating time from the mass of water in the container, the measured effective power output and a 55 °C temperature rise. Clause 8.3 then checks whether the container can achieve a useful heating result under the same conditions.

For the performance test, three containers are conditioned at room temperature, filled to 2/3 of usable capacity, heated for the calculated time and then checked for the rise in water temperature. The performance test passes only if each container reaches more than 30 % of the theoretical 55 °C rise. In practice, this helps separate containers that are merely safe from those that also heat food adequately.

Marking and reporting

Clause 9 requires information for consumers, including suitability for microwave use, spark risk, single-container heating where applicable, lid removal for metal lids, no metal covering, a 25 mm distance from microwave walls, free rotation checks where relevant, reheating instructions and burn risk. Clause 10 lists the information that must appear in the test report, including the laboratory name, the test sample identification, the measured effective power and the results of the safety and performance tests.

What terms does oSIST prEN 18372:2026 define?

• single-use container - a container not designed, made or placed on the market to be refilled or reused for the same purpose.
• container - an article designed to hold and protect foodstuffs and allow handling and transport from producer to consumer or user.
• packaging - the product's external or visible packaging, such as a cardboard backing.
• reusable container - a container designed to be used again without changing its original purpose.
• article - a metal or partly metal object, coated or uncoated, used as a container for foodstuffs or drinks during microwave heating.

Who uses oSIST prEN 18372:2026?

oSIST prEN 18372:2026 is used by test laboratories, manufacturers and suppliers of metal and alloy food-contact containers, and by quality or technical staff who need to judge microwave suitability. It is also relevant to organizations preparing consumer markings, labels or instructions for reusable and single-use containers.

The document is especially useful when a product is intended for reheating food or drinks in a domestic microwave oven and the question is whether it can do so safely and with acceptable heating efficiency. It gives a common test basis for product development, verification and reporting.

Which standards are used with oSIST prEN 18372:2026?

oSIST prEN 18372:2026 cites ISO 3585:1998, Borosilicate glass 3.3 - Properties. Clause 7 uses it to define the borosilicate glass beaker for calibration of the microwave oven, so the beaker material and properties are part of the power measurement method.

What does the oSIST prEN 18372:2026 document contain?

oSIST prEN 18372:2026 contains a full test method rather than a product specification. It includes the principle of the method, the apparatus list, preparation of test pieces, oven calibration, the operating procedure for safety and performance testing, marking and instruction requirements, and the test report content.

It also provides the formulae used to determine effective power output and theoretical heating time. Table 1 sets out the minimum consumer information for reusable and single-use containers, while Clause 10 defines what the report must record for traceability and review.

SLOVENSKI STANDARD
01-julij-2026
Materiali in predmeti v stiku z živili - Ocena primernosti izdelkov iz kovin in zlitin, ki
so v stiku z živili med segrevanjem v mikrovalovni pečici
Materials and articles in contact with foodstuffs - Evaluation of the suitability of metal and
alloy articles in contact with foodstuffs during microwave heating
Ta slovenski standard je istoveten z: prEN 18372
ICS:
67.250 Materiali in predmeti v stiku z Materials and articles in
živili contact with foodstuffs
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2026
ICS
English Version
Materials and articles in contact with foodstuffs -
Evaluation of the suitability of metal and alloy articles in
contact with foodstuffs during microwave heating

This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 194.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 18372:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle . 6
5 Apparatus . 6
6 Test pieces . 6
7 Calibration of the microwave oven: determination of the effective power output . 7
8 Operating procedure . 7
8.1 Determination of theoretical heating time (t ) . 7
test
8.2 Safety tests . 8
8.3 Performance tests . 8
9 Marking, labelling or instructions for use . 9
10 Test report . 10
European foreword
This document (prEN 18372:2026) has been prepared by Technical Committee CEN/TC 194
"Utensils in contact with food", the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
Introduction
This document specifies a method for checking the compatibility of articles used for reheating foodstuffs
in a conventional microwave oven. The main material of these articles is iron or aluminium metal, or
alloys of these metals – for example, carbon steel or stainless steel.
The power levels in question are similar to the maximum installed power of most European microwave
ovens and representative of those required for using the articles as containers for reheating foodstuffs
or drinks.
The articles are subjected to microwave energy in various positions in the oven cavity, in order to create
the most adverse conditions for heating and for distributing and concentrating microwave energy. As
most of the articles in question are made of metal, they should be used in accordance with certain
recommendations, including keeping a minimum distance of 25 mm between the article and any oven
cavity wall while microwave energy is being emitted, to avoid the risk of triggering the formation of an
electric arc.
The aim is also to advise against articles that take an abnormally long time to reheat for the user. As all
metal walls are opaque to microwaves, microwave energy can only heat up foodstuffs or drinks if the
article is technically designed to allow sufficient microwave energy to penetrate it.
This method aims to exclude:
– articles that could damage the oven, for example, by causing an electric arc to form, even though the
article is kept at a distance of 25 mm from the oven cavity walls while microwave energy is being emitted;
this may be caused by the article's unsuitable geometry;
– articles that may be damaged by microwave heating.
The articles are tested by being heated for a period of time and at power settings of the microwave oven
that are representative of those typically expected by a user. Specifically, a reheating time of about 5-10
minutes to raise the temperature of the article’s contents by 55°C (when the article is filled to 2/3 of its
maximum capacity).
1 Scope
This document specifies a method for determining the suitability of metal or partially metal articles
(coated or uncoated) used as containers for foodstuffs or drinks during microwave heating.
It applies to containers designed to be used once or many times with the microwave function only inside
the microwave oven.
This document aims to check the safety and heating efficiency of containers exclusively under
microwave heating energy, if other kind of heating are intended to be used for this container, it is tested
by considering only the microwave energy heating.
Microwave combination appliances, microwave ovens with impingement function and microwave with
an input power lower than 900W are excluded from the tests described in the standard. Furthermore,
any model lacking a protective dielectric barrier (such as a missing/broken glass turntable or a damaged
ceramic floor) that would allow direct metal-to-metal contact between the container and the oven’s
base is strictly excluded. In all compatible models, the use of the manufacturer-provided glass plate or
integrated ceramic base is mandatory to ensure electrical insulation.
This document defines the requirements for marking and labelling or instructions for use that are
provided to consumers.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3585:1998, Borosilicate glass 3.3 — Properties
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply
— ISO Online browsing platform: available at http://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1
single-use container
container that is not designed, created or placed on the market to be refilled or reused for the same
purpose for which it was designed
EXAMPLE        Tin can
3.2
container
article designed to contain and protect foodstuffs, in a single-use or used multiple times and enable
them to be handled and transported from the producer to the consumer or user. Foodstuffs may be
eaten directly from the container
3.3
packaging
product’s external packaging or visible packaging
EXAMPLE        cardboard backing
3.4
reusable container
container designed to be used again without any change in its original use
EXAMPLE        reusable stainless steel container
3.5
article
metal or partially metal object (coated or uncoated) used as containers for foodstuffs or drinks during
microwave heating
4 Principle
A container is filled with water to 2/3 of its maximum cap
...