 MikeV wrote: |
| I say rotate them from upright to upside down. Just my opinion. |
|
On the face of it, this looks like a good idea, but it only works with an absolutely clean metal to metal seal such as in gallon paint cans, and even there it causes problems when you next open the can.
For small jars of paint with screw lids, no matter how well tightened, something always compromises the seal. If nothing else, vibration slowly loosens the caps, and paint runs into the threads. (I know this from experience, because I tried it. I have enormous hand strength, and if I can't tighten a cap enough to prevent it, no one can.) The other problem is that many cap seals are made of coated cardboard. The solvent in the paint eventualy works through or around the coating, with obvious results. Even those paints such as Tamiya (and I think Gunze) that use plastic seals will have a problem, since these seals are not completely immune to the effects of solvent. The seals are usually made of polyethylene. Take a small polyethylene bottle, fill it with mineral spirits, cap tightly, and look at it three months later. You'll see what I mean.
And yes, I know places are selling mineral spirits in plastic bottles. I have an unopened one in the basement. The level of liquid in it has gone down about 1/8 inch in the last month. (I marked the side of the bottle when I brought it home, because I thought this would happen.)
So I think leaving jars upright is a good idea. You may (will) loose a little solvent, but that is the easiest thing to replace.
As a sidelight: Paint that comes in plastic bottles should be transferred to glass bottles for longer term storage (over six months or so) as soon as possible.