A GUIDE TO STUDIO SAFETY

How to Safely Dispose of Oil Painting Rags and Paper Towels

The spontaneous combustion that can occur with oily rags does not happen with rags used to wipe oil paint from brushes – otherwise, oil paintings themselves would be at risk, as they’re also cloth with oil paint. For combustion to happen, rags must be thoroughly soaked in oil and piled together in large quantities.

Drying oils (the vegetable oils used to make oil paint) dry by oxidation. Small amounts of energy are released, which is very slow burning. It is not enough to feel or be dangerous, unless a lot happens in the same place at the same time. The usual cause of spontaneous combustion in oily rags is a furniture factory with a big pile of rags completely soaked in oil from rubbing oil into furniture. It is unlikely to ever happen in a home or painting studio because it requires the rags to be completely soaked in lots of oil, not just some paint on a paper towel. There also needs to be a big enough pile to trap air in the folds and hold in heat as it builds up, especially on a hot day or if the pile is left in the sun.

If you want to be cautious, you can:

• Wash your rags (if they are cloth) and hang them flat to dry.
• For all your oil paint waste, use a covered metal bin that is half filled with water.
• Some people put their rag in a ziplock bag and push all the air out before they bin it, because it needs air to burn.
• If you get a rag soaked in oil – perhaps because you are oiling out a painting, or applying a layer of oil to a wooden palette – then you can lay your cloth out flat so it can't trap any heat in the folds.
• Wash your rags (if they are cloth) and hang them flat to dry.
• For all your oil paint waste, use a covered metal bin that is half filled with water.
• Some people put their rag in a ziplock bag and push all the air out before they bin it, because it needs air to burn.
• If you get a rag soaked in oil - perhaps because you are oiling out a painting, or applying a layer of oil to a wooden palette - then you can lay your cloth out flat so it can't trap any heat in the folds.

Cadmium paint is sometimes spoken about as being dangerous. Is this true?

As Gamblin Artist Colors explains: The cadmium used in artists' paints is a different form, chemically bound with sulfur, so it is stable. It almost seems like it should be called something different to keep people from getting it confused with cadmium metal.

Cadmium pigments are actually made from cadmium compounded with sulfur for the Cadmium Yellows (sulfur and zinc for Cadmium Lemon and Cadmium Yellow Light). To make Cadmium Reds and Cadmium Oranges, Cadmium is compounded with sulfur and selenium. American manufacturers of cadmium pigments have developed production systems that yield cadmium pigments that are relatively insoluble in the human digestive system. They have been so successful that Gamblin Cadmium oil paints do not require an ASTM health warning label for ingestion.

You can learn more in 'Cadmium and Cobalt Pigments and the Risks (or not)’ on Jackson’s Art Blog.

Safe art materials to take on an aeroplane

Oil paints, acrylic paints, watercolours, and gouache are all non-hazardous for flying. Only some oil solvents have a flashpoint that is below the temperature allowed.

Most airports do not allow liquids or palette knives through security, so you will need to put your paints in your checked baggage and not carry them on with you. Always check beforehand with your airline. Of course, you may be unlucky, and security staff may become alarmed by the idea of paints, wrongly thinking they are flammable. Taking Material Safety Data Sheets (MSDS) and being sure of your information may prevent them from disposing of your paints.

If you wish to use solvents, some are non-hazardous for flying. That being said, the security staff may not be convinced. You may wish to purchase your solvent at your destination, which would also avoid any chance of spills in your luggage.

What is the shelf life of art materials?

The shelf life of artist colours can depend greatly on the conditions in which they are stored and used. If the threads of the tubes or jars are wiped clean so that the lid can be fully screwed back on to remain air-tight, and the materials are not exposed to high heat or extreme cold, then the shelf life will be years.

Schmincke paint laboratories give the following general shelf life expectancies:

• Pastels: have the longest shelf life of all artists’ colours – nearly unlimited when stored in a dry place.
• Watercolour and Gouache: at least five years, usually much longer. A dried tube can be cut open, and the paint dissolved on the palette as if it were a pan. Old watercolour pans can usually be revived with a few drops of water.
• Acrylics: five or more years. This very much depends on proper storage. They must be kept moist by being stored in air-tight containers. They must not freeze, otherwise the consistency of the paint will be ruined.
• Oil Paint: has a very long shelf life if the tubes are airtight and undamaged. Some pigments can separate from the oil, even over a short period of time, but this is not damaging and the oil is easily mixed back in.
• Paper and Canvas: will last indefinitely if stored in a dry place and out of direct sunlight.

An article explaining the differences between many of the solvents available to artists

Read 'Solvent Safety Guide: Taking Care With Oil Paint Solvents' on Jackson's Art Blog.