Formaldehyde.... its safe use in foundries


This leaflet gives advice on current good practice

Phenol formaldehyde and urea formaldehyde resins are used extensively in the hot box and warm box processes to produce cores and moulds. The resins are mixed with a catalyst and sand which when heated, hardens to form a mould or core.

The hazards

At normal temperatures these resins do not give off vapour but when they are heated, formaldehyde is evolved which is a potential respiratory sensitiser and has been shown in experiments to cause cancer in animals. It is not however a proven human carcinogen. Formaldehyde can irritate the eyes, skin and respiratory tract and prolonged exposure could cause skin sensitisation and allergic contact dermatitis.

How to reduce risk

When using formaldehyde resins which are heated, local exhaust ventilation may be necessary.

Any worker who is involved in the use, storage or transport of these resins needs to be instructed on the associated dangers and necessary precautions. This may include the proper use of goggles, PVC gloves and aprons, and footwear.

Complying with workplace exposure limits

The current workplace exposure limit (WEL) for formaldehyde is two parts per million (2ppm), time weighted average over eight hours. The short-term limit (averaged over ten minutes) is 2ppm.

The WEL for formaldehyde is currently under review and subject to possible change.

A worker's exposure to formaldehyde should not exceed this WEL and every effort should be made to reduce the exposure as low as is reasonably practicable, and in any case below the WEL.

Regular checking and maintenance

It is advisable that local exhaust ventilation used to control exposure is subject to frequent checks for damage, in addition to the routine testing and examination, to ensure that it is operating effectively.

The duty of suppliers

Suppliers have a duty to ensure, so far as is reasonably practicable, that the chemicals that they supply are safe and present no health risks when properly used, handled, processed, stored or transported. They must provide customers with a description of the hazards involved and safety precautions necessary to overcome those hazards. This advice usually comes in the form of product safety data sheets and users are advised always to request copies from suppliers.

Advice given in these safety data sheets may form the basis for training and instruction given to employees.

Safe labelling and storage

Containers of formaldehyde resins should be properly labelled, stored in an area surrounded by a low sill to retain leaks and spills and protected from damage by passing traffic. They should also be stored separately from any catalysts, hardeners or sources of heat.

Dealing with spillages

Prompt action is required to deal with spillages and leaks. Suitable supplies of decontaminating materials should be kept available and employees adequately instructed on dealing safely with such situations.

Provision needs to be made for the subsequent decontamination of all protective clothing and equipment used in the clean up.

Waste disposal

Empty drums and containers should be properly labelled and stored in a safe place until they can be taken away by an authorised contractor for proper disposal. Alternatively, suitable arrangements may be made with the supplier for the collection of empty containers and drums.

Other available information

This leaflet was produced by the Foundries Industry Advisory Committee which advises on the protection of foundry workers from hazards to their health and safety while at work.

Further Information

Priced publications

Foundry hazard leaflets (free)

HSE priced and free publications are available by mail order from:

This publication may be freely reproduced, except for advertising, endorsement or sale purposes. The information it contains is current at 04/07. Please acknowledge the source as HSE.

Published by the Health and Safety Executive


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