Painting is nastier than virtually everything else a DIYer might do. It's all too common to hear of paint sprayers "retiring due to ill health", and sadly that ill health often involves debilitating asthma.
This page is intended as a summary rather than a complete guide to paint safety.
Cellulose is the paint most suited to DIY spraying. Apart from the advantages of fast drying time it is also much less toxic than other paints. (And it's much more tolerant to paint faults induced by DIY spraying conditions.)
A mask similar to the one in the photo can be bought from a paint shop for about £35 and is effective for cellulose paint. The carbon canisters in the mask will have use-by dates which should be respected (activated carbon filters do go off so don't just use an old gas mask - it may be useless). It should not be possible to smell the paint when wearing these masks, and they require a clean shaven face for good sealing.
Skin and eyes should be covered as nitrocellulose and thinners can also be absorbed into the skin. They can cause headaches and make you high.
An air fed mask is essential for 2-pack (2K) paints. It will consume at least 7cfm of air, so cannot be run together with a spray gun on a 3hp 14cfm (9FAD) air supply. The air supply is important - it must be breathable air (see below).
2-pack paint is really nasty stuff - it gives you occupational asthma when you breathe it in. See the HSE (Health and Safety Executive) pages on occupational asthma, and their page specifically about spray painting.
Some suppliers falsely claim a filter mask can protect against 2-pack paint. It's you doing the spraying not them - read the links above and take proper precautions when applying any 2-pack paints. Have a read through the experience of a forum member who sprayed 2 pack without an air fed supply (fortunately he is still alive, but will have the asthma for the rest of his life).
Breathable air supply
The air fed mask is only a small part of the cost of an air fed mask. It should also be supplied with breathable air as any water or oil contamination in the air can result in pneumonia.
- The compressors air intakes should to be sited away from contaminated air
- The air system should have effective water removal
- The air should then be filtered to remove contamination down to 0.01 micron
The photo shows a typical filter set for use in an air fed mask (thanks Snowcat). A fine filter by itself would be quickly blocked, so it is protected by a coarser filter upstream which itself is protected by an even courser filter. The filter pack itself is protected by a water trap.
Overalls and gloves
Disposable paint overalls are cheap and will cover the whole body apart from the face. Disposable gloves should also be worn. Together these protect the skin from paint. Nitryl gloves seem to last longer than latex when covered in thinners during gun washing, but neither stand up to thinners for long.
Gloves and overalls also protect the vehicle from lint from your clothes and oil from your fingers. Paint shops tend to have changing rooms as taking the overalls outside the paint shop might result in contamination.
Fires and explosions
Paint vapour is explosive. Open flames and heaters other than infra-red paintshop heaters aren't a good idea. Filament light bulbs will expose a red hot filament if they go pop so should also be avoided. Likewise a 500 watt spotlamp can run so hot that the glass cover can ignite paint vapour. Strip lamps are OK as are specially designed painting lamps.
Plastics that are not designed for a paintshop can spark. Even throwing waste into a bin bag can cause a spark which is especially troublesome if there are any paint containers and heavier than air fumes in the bag.
Safety of others
A paint booth will have air filtration and contain only the painter wearing protective equipment. For a DIY garage in a built up area 2-pack paint cannot be used sensibly as the fumes seeping out of the workshop can be enough to cause problems for people with existing lung conditions. A garage attached to a house causes further troubles - if you can smell paint it's not likely to be doing you (or the wife, cat or goldfish) much good.
For these painters 2-pack isn't a sensible option. If a 2K top coat is essential then prepare and fill the car then take the car to a paintshop. Cellulose paint is more benign and much less likely to cause health problems for neighbours or bystanders.