How to fill pinholes and bubbles in resin molded slot racing bodies?
Not having them in the first place is the best way ... Absent that it kind of depends on where they are and to what extent. If it is a pinhole or void, or very thin area (big bubble that "skinned") I've had good luck filling these in with some modeling putty. If it is a larger area it is good to back the area with some thin styrene sheet superglued into place as a base for the putty. As always with putty--thin coats is good, big lumpy blobs (like I do) are bad. If the "bubbles" are the kinda cottage cheese variety where it looks like an all-over blemish in an area (or the whole part), my best luck has been to lightly sand the area(s) affected and carefully spray on primer to build up a bit then sand back to level. Care must be exercised here to avoid burying detail in primer (see thin coats/thick blobs above, keeping in mind which side of the fence I preach vs which I usually follow). [Scottrik]
Question : What is the best primer to prepare resin slot car bodies for painting ?
I've had very good luck with both Duplicolor "Sandable" Primer (I prefer white unless I'm painting over pre-existing tampo printing, etc, then gray) which is available in large aerosol cans at many auto parts stores. My current favorite is Tamiya's white spray primer as it is VERY fine and usually needs no sanding before hitting with color. Works very well, but is a bit expensive... [Scottrik]
Question : What techniques can you use to make resin body molds without sticking to the original body ?
To save a body from the clutches of the resin stick destruction, back pour the body with a Hydrocal or fine plaster of paris after using a cooking spray such as Pam to help separate the body much easier from the plaster. It does not stick as hard as it will with the resin. Then work the resulting plaster cast over if you want changes or to add details. Then use an RTV type rubber to cast a thick mold in a box type holder. When cured you can then pour your resin in the mold for a slosh cast of the body in resin. Do it thinly the first time and get it to keep flowing till it starts to thicken up then make sure you have no real heavy or deep spots where you don't want them. If the result is not quite thick enough in some places do another slosh pour, being careful to not leave too much in other areas by keeping the mixture moving until it sets up. This will take some practice. And the original body should clean up with some soap and water, no worse for the wear if you were careful. The plaster mold should be coated with the recommended release agent for the brand of rubber you are using. Because the mold rubber is flexible it will release from the mold much easier than the vacuum formed body will from the resin casting. You want to make the mold of rubber thick enough so that the mold will not distort when the resin is poured into it and you move it around while sloshing the resin. Or pouring a solid resin mold if you want to, as I do to make a vacuum mold up of solid resin. Getting the vacuum formed body off the plaster mold should be easier. But much depends on how much wrap around the original body has. If it has tumble home on all four sides, it can be difficult to get it off without some damage. What I have done before is take the body and mold under a light bulb and gently warm up the vacuum formed body till I can gently pry it off one end first then work my way around the body leaving the deepest end for last to slide it off to the rear of the mold. Takes some work and patience but have saved a number of pretty tight wrapped bodies off the molds. Then there are some that are just to far wrapped around to save. [Larry S.]
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