How Not to Get Rust Flakes in Your Paint

tldr; Use a rubber mallet, not a hammer, to close your paint cans. Don't allow paint to collect in the rim or it will rust and ruin your paint. Also its best to use a paint tool instead of screw driver to remove the lid so it does not deform. If this does happen then read on.

I started some trim paint work a few months back and recently when I opened the can I noticed rust all over the lid. I painted with it and sure enough there were rust flakes here and there on my trim. This sucks! I went to the local paint store and the salesguy looked at me like I'm just a biggest moron he's ever encountered. He wasn't able to articulate the why it happened but I figured it out. I was closing the paint lid with a hammer. This deforms the lid and when that happens you get air pockets where the lid meets the can. The ingredients for rust are #1 Steel, #2 water #3 air. Second mistake was to allow paint to collect in the top of the can where the lid goes.

So, to resolve this issues, with Ben. Moore paint at $50 a gallon I'm not interested in tossing it. I bought an empty can for $3, a mesh filter, and poured the paint from the rust can to the new can, through the filter. I'm not certain the mesh was fine enough to filter out the rust but we'll see. I'm only using this paint for the first coat so if it does still have rust then I can sand and remove before the final coat. The guy at the paint store mentioned that panty hose can also be used to do the same thing.