Plugging Pinholes

Pinholes are the plague that infects resin kits - they are caused by tiny air bubbles in the liquid resin floating to the surface as the resin cures. More sophisticated casting processes are being developed which help reduce the the amount of bubbles, but these are often restricted to the more expensive kits.

For most, bubbles and pinholes are a fact of resin kit life. Until now, I've been unable to find a quick & easy process for dealing with them - larger ones (0.5mm and up) can be painstakingly drilled out and individually filled with putty, but this can become ultra-tedious when you are faced with hundreds and hundreds of the buggers.

Liquitex produce a thick acrylic that is designed for adding form and texture to paintings, which makes it an ideal medium for creating basework. You just spread it on and let it dry. It can then be easily carved and sanded into more intricate shapes. I bought a tub and began experimenting with it on a few old scrap bits of wood and then suddenly wondered how well it might fill the dreaded pinholes.

Using an old, stiff brush, I stippled the paste across a particularly badly infected kit part ( the lower jaw from Grey Zon's Godzilla Skull) and then before it dried (here's the advantage of an acrylic paste) used a piece of rag dipped in water to wipe off all the excess. Bingo! all the holes were and the surface was smooth - and all in a matter of seconds. After the paste had dried for an hour or so, I shot another coat of primer over the treated area and the results were perfect!

Helpful Tools:: X-ACTO knives with a variety of different blades
Variable speed motor tool such as a Dremel with an assortment of grinding and cutting bits
Sand paper or sanding films of different grits, coarse to fine.
Foam backed sanding sticks (I love these things). A great place to find these are in the nail care section in the beauty supply area at the local discount drug store. I like the ones that are about 3/4" x 7" with four different grits on them. They are cheap and indispensible!
Glues: Regular plastic model glue will not work on resin kits. They work by acting as a solvent that melts the plastic together. Resin doesn't melt. You must use a cyanoacrylate adhesive (super-glue). The thick types such as Zap-A-Gap work well. It also helps to use a kicker to speed the curing of the glue. I usually apply the kicker with a toothpick or bamboo skewer rather than spraying. Five-minute epoxy also works when you need added strength or a longer work time.
Puttys and seam filling: Almost any putty that you normally use on plastic kits will work on resin. Automotive Glazing and Spotting Putty is good for minor imperfections such as pinholes. This putty drys quickly, is very easy to sand and a tube will last forever. Epoxy putty is great for larger gaps. It is a two part system that, when kneeded together, can be worked like clay. You generally have a couple of hours to work it before it sets up. The biggest advantage this has over other fillers is that it can be worked and smoothed with tools and brushes dipped in water to produce a finish that will require very little sanding. An excellent one is made by MagicSculp.