This picture of a metal fabrication plant fire is here to make a point... OILY RAGS MAY CAUSE A FIRE!!!

I took this photo of the fire several years ago in Cannon Falls, MN.
As painters we constantly need to wipe our brushes on something to clean them, a dilemma on several levels. The first dilemma is and should be safety first. Any combustible material that is saturated with an evaporative solvent or oil is a fire hazard waiting to become a fire if not handled properly.
This info is from a Colorado Fire Dept. web site...
"What Is Spontaneous Combustion?
The Encyclopedia Britannica defines spontaneous combustion as the outbreak of fire without application of heat from an external source. This combustion can occur when flammable matter like oily rags, damp hay, leaves, or coal is stored in bulk. Spontaneous combustion, sometimes referred to as spontaneous ignition, begins when a combustible object is heated to its ignition temperature by a slow oxidation process. Oxidation is a chemical reaction involving the oxygen in the air around us gradually raising the inside temperature of something (like a pile of rags) to the point at which a fire starts.
Spontaneous Combustion Can Cause Fires
While spontaneous combustion isn't a common occurrence, it can be disastrous. Spontaneous combustion causes major fire losses each year. One of the most common scenarios is when floors or woodwork are being refinished and stain-soaked rags are left in a heap on the floor. Something as simple as not storing these rags properly can cause major fire damage.
In fact, the way combustible materials are stored has a lot to do with whether or not they'll spontaneously combust. For example, while an oil-soaked rag stored in a pail could heat up enough to burst into flames, the same oily rag laid flat to dry would probably have sufficient airflow to prevent heat buildup. Similarly, if the oily rag was placed in a tightly sealed jar, it most likely would not have sufficient air to allow the oxidation process to occur. That's why it's a good idea to look around your garage, storage shed, and yard on a regular basis to ensure that all flammable materials are properly stored. "
These thoughts are my own, I'm not suggesting that anyone take my information as the correct way. There is a plethora of information on the web concerning the safe use and disposal of oily rags and spontaneous combustion. Please read about it if you aren't familiar with the issue BEFORE you use rags of any kind, paper towels included, for cleaning up your oils and paints.
One product that will take care of the paint that we want to clean off of our brushes is paper towels; a paper product that is not only getting expensive, but that also results in a lot of 'throw away' waste that doesn't do much for making me feel like I'm being conscious of our natural resources in my painting methods and materials. I would guess that it's safe to say that most of us use paper towels, they're convenient.
The other, older solution is to use the old fashioned 'RAG'. I'll admit that I was watching a Morgan Weistling DVD, he uses rags, and that got me to thinking about what I use to clean those brushes. I decided to give rags another shot and am happy that I did. I'm not going back.
The affordability and safety of rags are what I started thinking about. Rags need to be absorbent, cheap, and as I realized, reusable. I have been buying them, terry cloth wash clothes at a local retailer, 18 for $4.00. But this summer I'll be hitting garage and rummage sales for T-Shirts, towels and flannel sheets that are CHEAP. There are a bunch of different sources for rags that are so much cheaper than paper towels. The paper towel expense is like throwing away money, use them up, the investment is gone. I know, it's part of the cost of the painting. Hey, cut that cost and make more money on the sale!!!
Rags, on the other hand, will last for many, many uses and do not eat up any our precious natural resources. Yes, it takes land to grow cotton, there's always a trade off but that's one that is less critical in my eyes than the overuse of our national forests for paper products.
Then there's safety. To solve the issue with paper towels I used one of those omnipresent plastic grocery bags for each painting session and it went to the outside garbage can, away from the house because they can still combust in there, at the end of every single day or painting session.
There are special fire safe cans, called Red Cans, that are made specifically for disposing of oily rags. You still need to empty that nightly.
So what to do with cotton rags then??? I ran across a Q&A site for 'garage heads', people who spend a lot of their time working on cars in garages, that had a great solution that I'm using. I'll mention that one following this...
Another site was for woodworkers who use a lot of rags to stain with oil based stains and solvents. Their solution is to use a 'drying rack' that allows the rags to be hung, not touching the other rags or themselves, with complete air circulation all around them. If the air is moving sufficiently around the rags, the air carries away the heat that does build up until the oil or solvent is completely innocuous, and the fire hazard is subdued. This is a pretty good solution, but I would like to be able to clean the rags too so that I can reuse them and not have to purchase more very often. $$$ Savings$$$
Other information suggests putting the rags in an airtight can with a lid, covering them with water and then taking them to a hazardous waste center for disposal. Again, safe but the disposal of them means that they can't be resused.
The solution that I am using, and the one that made the most sense to me for my needs, is from the 'garage head' Q&A site. They suggest that the rags be washed in a washing machine with 'SIMPLE GREEN'. Simple... but I am not about to wash my oily rags in the same washing machine as my oily painting clothes!!! ;-) My clothes aren't that dirty, just kidding. Not in my washing machine though.
What I do is this... At the end of a session, I put the rag(s) (I usually only need one rag per session) into a lidded, one gallon ice cream pale, full of concentrated 'SIMPLE GREEN' for an overnight soaking. In the morning I take them out, rinse in the sink with hot water and PRESTO.... they're clean and ready to be hung up or laid out to dry in preparation for another painting session!
I wondered then about the waste water from doing that. I'm comfortable with it for several reasons. Any water from the washing machine, sink, car washing in the drive way... is gray water and needs to be considered as eventually impacting our water supply. Not that I am happy that 'any' residue is present at all, I'm not. But I am comfortable in that the amount of residue from cleaning these rags is minute compared to what runs off of a driveway when the car gets washed. In a perfect world, neither would result in any run off.
On top of that, I'm using about 8 rolls of paper towels a week less! That's a lot of wood product saved.
If you made it all of the way through this post, you are one SERIOUS artist! Thanks for reading. I hope that it helps you keep your studio safe, and that you find an alternative to paper towels a good thing.