I did not get to post a blog last week because I was devoting some extra time to my art and craft projects in order to gear up for the holiday season...and THIS week I've been preparing for the ever so fabulous Learning and Product Expo in Pasadena. October is always such a busy month! My apologies to those of you who check in regularly for postings, I promise next week I'll get back on track!
I've been dealing a lot lately with the issues associated with the temperature sensitivity of my acrylic paint films. This is one acrylic "horror" that is just SO disappointing when it happens, especially since it's so easy to prevent. You spend ages on a project, or maybe just minutes, but you've perfected your image and are ecstatic about the outcome...then the unthinkable... your project somehow pressed itself face-first against another painting project and they are sticking together. You might react quickly (in the case of a recent coaster set prototype I was making) and pull the images apart, then *gasp*... a piece of one surface transfers to the other surface, putting a gouge into the paint film.
In the case of the coaster set I was making, I stacked them face-to-face and back-to-back in order to protect the images from scratches. I was only storing them this way for a day or so, so I figured I didn't need to slide any additional non-stick protective coating in between the coasters.
A lot of students ask me about the "tacky" quality of acrylic paint, as this is a big issue for us here in southern California where the climate is warm most of the time.
Acrylic paints are thermoplastic, basically meaning the paint film softens when warm and hardens when cool. When the paint film softens, it remains tacky, even after the paint is dry. You could have an acrylic painting that has been dry for years start to feel more sticky when exposed to heat.
When these paint films have softened, the are quite vulnerable so it's best to always store and transport your art projects with a protective barrier between them. Vellum and glassine work well and are easy to find at your local art store or through online ordering.
In the case of my coasters, the sealer was dry but when I stacked them face-to-face they stuck together under a mild change in the warmth of my studio.
If your surfaces are sticking together and are small enough to fit in a freezer, you can hold them in there for a minute or so then try to pry them apart with minimal surface damage. When the acrylic films cool down, they harden... those of you in cold climates need to be careful not to try and roll or unroll your paintings when they are cool/cold or else they may crack! By putting your bound images in the freezer, you reduce the tack of the paint film therefore giving them more ease of release from each other.
To reduce the tack of your paint film during the application process, try adding GAC 200 or GAC 500 to your paint! Read more about these Special Purpose Polymers here: http://www.goldenpaints.com/products/medsadds/polymers/index.php
I will certainly remember next time to put a barrier sheet between my coasters. It takes seconds to prevent the films from sticking together, which is much better than spending another hour making a new coaster set!