A Softcup is comprised of a flexible rubber ring that stays in the default position of a circle when not being squeezed and a thin "plastic" cup (I don't actually know if it is technically rubber or plastic but its close and that gives you the right idea). On a flat surface the pink rubber ring gives it a nice airtight seal. The cup is waterproof and therefore pretty airtight as well.
If you are a painter, who has ever squeezed out too much paint, mixed a dollop of paint that you didn't use or worked with acrylic in a hot room - you know that a lot of paint drys into little hard balls of worthless plastic. This is true of oil as well (well not balls of useless plastic) but useless bits of crusty stuff that once began its painting life with colorful promise. With acrylic though, its a constant battle, even with a little spritz bottle to occasionally hydrate the surface of the paint, I loose some.
So there I was in my studio chair in intense study of the strange little pink plastic cup and in a moment of true divergent thinking it occurred to me that this plastic cup was not entirely unlike a large dollop of acrylic paint mounded up in an irregular dome. "This thing could keep paint wet for hours" was my first working hypothesis but little did I know, this thing can keep paint wet for days.
The Test.
On Monday March 10th at 5:30p.m. I squeezed out two dollops of Liquitex BASICS primary yellow. I spritzed water onto the Softcup (not a great deal mind you) and placed it over the dollop on the left. I checked 3 1/2 hours later and the paint was wet in the Softcup and getting firm on the exposed dollop.
I checked again the next day March 11th at around 11:30a.m. The exposed dollop was completely dry and exited our test and therefore our story as a little hard ball of worthless plastic. The Softcup dollop however was still as wet as if it had been just squeezed out of the tube.
Again I checked the Sofcup dollop at 11:30 a.m. on March 12th - still completely wet. 11:30 a.m. March 13th - still wet but firming up. I did not spritz water inside the cup on March 13th.
On March 14th at 11:30 a.m. the paint was dry. The paint stayed wet inside the Softcup for roughly 3 days and would have lasted longer if I had spritzed more often. Conclusion: These little plastic cups are fantastic at keeping air out and therefore paint wet. I know that some people will say that this is not as useful as plastic wrap or Tupperware etc. Well, possibly but the problem I have always had with plastic wrap is that it has no shape but as you see in the following picture the Softcup is very similar in shape to the paint dollop. Tupperware is often too big for the amount of paint I am trying to keep wet.
As a final thought, Softcups are not very expensive as they never actually get very dirty, they are infinitely re-usable. Give them a try and you might notice from the picture above, they also fit nicely over a small aluminum can. The only downside to these new objects in my studio is the oddly disapproving looks that I seem to get from, well everyone. Perhaps I should stop making everybody hold one.