While ordering a few things related to another hobby of mine (electronics), I noticed a product announcement that got me curious about its applications in “our world”. The product description intrigued me:

“WonderMASK P2 is a peelable temporary soldermask with unprecedented drying speed, increasing throughput and saving money. Techspray coordinated with several PCB manufacturers to develop a mask with all the features needed for modern, high speed operations.”

I won’t repeat the whole list of product features -- since some are of more interest to manufacturers of printed circuit boards -- but these features intrigued me:

· Peels easily with no residue.
· Low odor – Less need for special ventilation.
· Cure indicator – darkens as it cures.
· Easy to apply by hand or machine.
· High viscosity – Will not run or mushroom under through-hole.
· Easy disposal – Once dry, can be disposed as low hazardous waste.
· Long shelf-life – Will not go bad in storage.

I was curious enough to request an 8-ounce squeeze bottle of the stuff. I wanted to find out if it was going to be useful for two scale modeling tasks: masking things off for painting purposes; and also trying to use it as a brush-on rubber to make small molds with, for casting purposes.

I expected a “learning curve”. Any product that involves chemistry will require some experimentation to figure out its strength and weakness, and how best to use it. While I didn’t extensively torture-test the stuff, I was pleasantly surprised at how well even my earliest tests went.

My initial paint-masking tests showed that even a “hot” lacquer-based automotive spray can primer (Plasti-Kote’s sandable gray) didn’t harm it in any noticeable way. When brushed over a smooth surface, in a relatively thick layer (about 1/32-inch or 2mm), I found that it peels back off with just a gentle scraping or rubbing with a thumbnail. (And you can sometimes just roll it off with your thumb, after getting an edge to come loose.)

Where I had applied WonderMASK in a see-through, paper-thin coat, it still did a fine job of masking things off. The only problem I noted with very thin layers is that it was more trouble to scrape it back off, afterwards. It did all come back off, mind you; using only a thumbnail: it just took more time and wasn’t as easy.

I didn’t notice any problems with the surrounding paint peeling up. As a paint mask, it seemed to do the job well. (Which is not all that surprising, since it’s designed to be an effective masking agent for applying molten solder!)

My initial mold-making tests also went well. I’ll have to play with it more -- to see how it holds up to casting resins, etc. -- but as far as simply brushing the product on, to make a thin-walled mold: I liked those results. It was thin enough to brush on easily; yet thick enough that it didn’t “run” off, or make a mess. It stayed where I put it. It seems to have captured all the small detailing well.

I didn’t notice any unusual problems with bubbles either. Just brush the stuff on a little at a time, to avoid trapping a bubble that might cause a distorted casting.

The only problem I’ve had so far was due to trying to see what would happen if I ignored the instructions, and tried to apply it in an eighth-inch thick layer. (The outer half cured, the inner half didn’t.) Further experiments showed that if you’re not overly greedy, and you apply one layer at a time, you can build it up into a thicker “mold wall”. It dries quickly, so that shouldn’t be any real hardship.

I didn’t intend to, but I also tested the “long shelf life” claim. (It’s true.) The squeeze bottle sat for three or four months before I got around to using it. Still seemed to work as advertised, as far as I could tell.

The only thing that concerns me is the “poison” labeling on the product. Then again, a lot of hobby chemicals have similar labeling -- and common sense should always be used.

I feel Techspray’s “WonderMASK P2” could be a very useful product, with a lot of scale modeling potential. I look forward to other folks trying it out, and reviewing it.

Thanks much to WASSCO for supplying my review sample! Wassco order#: WAS-01-042219. (2220-8-SQ Squeeze Bottle.)