Painting of any sort is an expensive occupation. If you follow good practise there should be minimal waste, and safe disposal of anything that has to go. This is good for your pocket, and the environment.
Recently I read a blog by Tegen Hager-Suart, on the Jackson’s Art Supplies website, about artists reducing waste and minimising their environmental footprint. This made me think about what I do. I mainly paint with oils so this guide is about oil paints.
No paint waste should be poured down the sink; it can damage your drains and the water supply. Disposing of hazardous material into your household waste is illegal. Pouring it onto the ground damages the environment and is bad for the soil. Paint waste needs to be disposed of responsibly.
The solvents used with oil paints, and the paints themselves, contain chemicals that need to be disposed of responsibly. Avoid getting them on your skin if you can.
Try to reduce the amount of waste you create, buy sensibly, look after your equipment, don’t let being sensible hold you back.
Steps Towards Reducing Oil Painting Waste
Part of the joy of painting is experimenting, exploring and being inquisitive. It would be sad to lose this because you are being careful about waste. This is a dilemma everyone must work out for themselves.
There is a balance to be struck between creativity, cost to pocket, and cost to environment. Do you bulk buy paint, solvent, canvases etc to save money? If you are lucky enough to have storage space and can afford the initial outlay this means less packaging and carriage. Unlike food from a cash and carry most oil painting materials aren’t going to go off.
Do not forgo all impulse purchases – a strange green, or different oil – because it might not get used; it might take you to new worlds!
Paint
Think about the quantity you put on your palette. It is easy to sound like Goldilocks …”not too much, not too little, but just right”…Nobody liked Goldilocks but she had a point.
Make sure you clean the tops of the paints before the lids go back on…this should stop the lids getting stuck or air getting in.
If the tops are stuck carefully pour boiling water over them, they should open. Pliers, or nutcrackers, are useful with a good grip.
To get the last squirt of paint from a tube put the paint on the floor, with the lid tightly fixed, and gently, using your foot, press the paint from the bottom of the tube to the top. There is always more there than you think.
Solvents, Cleaning agents, Mediums
Use airtight, none plastic containers to store oil solvents.
Pour out into small containers the amount of medium/solvent you need for that painting session. I use jam jars with lids. If the solvent gets grubby leave it to stand, with the lid on, and the residue will sink to the bottom. Decant into a clean jar and use again. The gunge at the bottom can be used as a ground, or for underpainting.
Good practise, minimal waste, safe disposal
At the end of the day, if you want to use the paints on your palette for the following day, tidy them into more compact dollops (I’m sure there is a better word). This reduced the area exposed to the air, and to drying out. I often put clingfilm over the palette – I think greaseproof paper would be of a smaller footprint.
Brushes
Remove paint and pigment from brushes using a rag. Use two rags if that helps. The idea is to put as little paint into the solvent as possible.
Try to avoid letting the paint dry in the brush. This makes it difficult to remove and so the brush becomes unusable and you may have to throw it away.
Oil Painting Clearing up
Wipe brushes thoroughly with a rag or piece of newspaper.
Soak the brushes in a brush cleaner that contains solvent or a slow-drying oil such as vegetable oil. In Spain We use the most delicious olive oil from the estate – scandalous really but it is readily available. The paint residue will settle at the bottom of the liquid.
I use a bar of laundry soap for cleaning my brushes. 
In a ceramic bowl wash the brush with a mixture of soap and warm water. Wipe the brush on paper or clean rag. Wipe the dirty water out of the bowl with a rag and dispose of it. Remove the soap from the brush and let it dry before your next painting session.
Brushes should be dried in a horizontal position or suspended with the tips facing down, this avoids moisture running into the ferrule and causing the wood to swell.
Store hog hair brushes in a well-ventilated room, out of direct sunlight so that the hairs can breathe and not attract mould.
Palette
Clean your palette by scraping any excess paint into a newspaper and transferring this to a sealed bag.
After scraping away excess oil paint off the palette, you can wipe off the remaining paint with a rag followed by pouring a small amount of oil on the surface and wiping that off with a rag.
Once oil paint has dried you can also scrape it off the palette using a palette knife or metal scouring pad. The dried paint can be put into a sealed bag which can then be disposed of.
Disposing of Oil Paint and Solvents
Oil paints, oil solvents, and rags that have been soaked in these, count as hazardous waste and cannot normally be disposed of in household waste. Your local council will be able to advise you where to take hazardous waste in your area. Often local dumps have a paint disposal area.
Think – Good practise, minimal waste, safe disposal
Be aware that the fumes from evaporating oil solvents are toxic and if inhaled can cause dizziness and nausea. I use vegetable oil as much as possible in the place of solvents.