(This post has no photos because I didn’t think it was as brilliant an idea to blog about before I did it – but my technique worked so well, I have to share it.)

So you left the paint in the garage or in the cold cellar and it froze and now you have lumpy paint. Congratulations! Lumpy paint is a pain in the neck, and also fugly to take a picture of. (Bonus, if the lumps are pigment — mine were making nice blueberry smears until I mixed it well and painted over them.)

You could roll that lumpy paint on the wall anyway, and use a putty knife to take the skins and lumps off while it’s still wet. Or, when it’s dry, use a wall sander (like you’re supposed to!) or a sanding block to knock the lumpy bits off. Don’t rub too hard, or you’ll mess up the otherwise smooth finish.

Still, I betcha don’t want to roll lumpy paint on the wall. You’d rather filter it, right? But you either don’t have a screen sieve of the right gauge, or you don’t want to use one from your kitchen. So here’s what you do:

All 10-pound potato sacks have a nylon screen window. If you don’t have a 10-lb bag of potatoes, go buy one or ask your friend or neighbour for the bag. Do it.

1. Cut the window out, leaving a good margin on the paper bag edges.
2. Take some packing/masking/duct tape and tape the window around the top edge of the paint can, on the pouring side, of course, not with the handle in the middle. Don’t tape it too hard because you might need to remove it after pouring. You don’t even have to tape it at all, but it helps.
3. Tuck the edges with tape or your fingers to cup the window screen slightly.
4. Mix the paint well! Make sure it’s consistent, lumps and all.
5. Pour the paint   s l o w l y  through the nylon screen into the paint tray.
6. If you’re not emptying the can, then as you upright the can, remove the screen and pinch the corners together. Place the screen on the lid of the can or support it above the can so that it can drip. You can use your brush to encourage the lumps to give up the last of their good paint.

At the end of painting, you can throw the screen out, finish the paint in the can, and recycle the can.

Here’s what happens to it in the environment:

In an aerobic environment, the paper biodegrades, and so will latex or linseed oil base paints — fungi and bacteria digest these. Even petro-chemical-derived paints biodegrade, but you can still find paints made in a traditional way.

However, not a lot of landfills are aerobic environments, so… I don’t know how they’ll decompose. Landfills produce methane – a harmful greenhouse gas, unless the landfill company harvests it for biogas fuel.

Then there’s the nylon screen, which is a little problematic. It will stick around for 30-40 years (less time than a plastic bag, but still). But it was manufactured for another purpose, and you just reused it…which is good.

The thing that worries me the most about nylon in the environment is that we have tons of “ghost” fishing gear abandoned in the oceans, tragically maiming and killing marine life. And in terrestrial ecosystems, we stake nylon nets to hold down mats of sod on slopes, to prevent the slope from eroding until the vegetation takes over to hold it in place. The sod that turns into a grassy, weedy hillside will be encased at the surface and root level by a nylon net. While it’s still strong, it will trap and maim a few field mice and other animals. Landscaping ought to be more ecological.

Recycle old paint

Keep in mind that biodegradation is a process that works on organic compounds; the minerals — like zinc and titanium — in the coatings and the pigments stick around. Even if there was no other way to use them again than in paint (whether they get recovered from paint to use elsewhere is doubtful), trace elements cannot be recovered from the environment. They can’t be mined again.

All of which is why it’s important to recycle old paint, and not throw it out. Particularly if you can’t be bothered dealing with lumpy paint!