Can I keep unused paint in the roller tray? [solved]

As long as you can get it airtight, it will work just fine. I use the disposable tray liners and try to get as much of the paint off the liner as possible, pouring the remaining paint back into the can.

I leave the liner on the roller tray, cover it with plastic wrap and then put the whole thing in a tie-off garbage bag, trying to get as much of the air out as possible. Keeping it in a cool place helps to cut down evaporation too.

Another tip: 1 gallon Ziploc freezer bags are the perfect size to hold a 9" roller cover between uses:

I squeeze the roller cover out with a painter's multi-tool, drop it in the bag, and seal it up. It won't keep forever, but it will certainly last a week.

I appreciate your effort to save some work with the left over paint in your trays. I always use the disposable tray liners. Tray liners are so cheap, use them. Pour as much as you can back into the can and use your edging brush to direct the paint out of the tray liner into the can, then throw the liner away. If you leave paint in the tray( with or without a liner) I guarantee the thin edges on the sides and spreader area on the tray will get gummy no matter how you try to seal it up, then let flakes loose next time you use it, get stuck on your roller and ruin the rest of the paint in the tray, your roller cover and the job you are working on. My advice is to spend 50 cents on disposal tray liners and save yourself a lot of hassle. You can however seal your roller covers in a plastic bag. Squeeze out ALL the air and wrap them tight, completely air tight and they will be fine for a few days, even a week. That can save a lot of clean-up. I rarely clean rollers, I seal them, and when they get even a little sticky, throw them away, even Purdys!!! Cost of doing business. Brushes however, I use a wire comb and clean them after every hour of use, and after the day is done. A good quality brush can last a year if well cared for.

I find is much easier (during painting, cleanup, and short term storage like you want), to use a 5 gallon bucket and a vertical screen for rolling. Pans are very cumbersome, prone to spillage, and over-saturation of paint on your rollers. When rolling, most professionals use these over pans.

In your case, you could just leave the roller and screen in the bucket, put the lid on, and come back next weekend ready to roll.

The screens are like $5 and you may already have a 5 gallon bucket at home, or but a new one for like $2 at the closest mega hardware store. If you put a roller extension stick on your roller, you can even apply paint without having to bend over.

Here is a how to from This Old House on how to roll like a pro.

When you really want to put paint on a wall quickly, nothing beats a roller. To improve on that efficiency even further, lose the tray and get a 5-gallon bucket equipped with a roller screen. The bucket holds plenty of paint, you won't step in it by accident, and the handle makes it easier to carry than a tray so you can keep it close by. A bucket also lets you "box" your paint—pour like-colored cans into a single container to even out any minor inconsistencies in color.

Here is another good artice talking about rolling from a can.

I have in the past put the roller and tray in a bag and found it kept OK overnight so allowing me to do the 2nd coat with only one set of cleaning up. There is no need to get rid of all the air, after all paint tin has some air at the top of it. (I have never tried more then "overnight")

The other related “trick” I have found, is to:

• Do all the prep first,
• Then “edge” all the walls with a paint brash
• Then often I can do all the rolling in one short day, as the rolling is the quick bit.

Re-using Dirty Paint Trays (or How To Instantly Clean Paint Trays)