JohnW

My Feedback: (6)

I have a plug (first large plug thread) that is nearing completion. I’d like to make parts that are painted in the mold. Ideally, I’d like a gloss finish on parts, but I would settle for a satin finish.

I’ve searched this forum and other web sites on the process, and found some info, but I would like to get the best finish with what I have on hand. I’m sure there are special made products, but I’d like to keep my costs down by working with what I have on hand, even if that means I have to compromise some on finish. I’m not looking for perfect, just the best I can produce with the time and materials I have.

This is what I’m working with… The plug is primed with PPG Omni 282, which is a high build catalyzed primer. I sanded a test object running up to 1500 grit and actually was able to obtain a shine from the primer, which leads me to believe I don’t need additional finishes to obtain a fairly decent mold. Am I right here, or should I top coat with something else?

If the primer I used is OK for finish, has anyone tried to buff with rubbing compound to get more gloss? Will the primer benefit from this process?

If the urethane primer is not ideal as the finish coat, I have some PPG 182 epoxy primer, base coats and high solids urethane clear coat. Would any of these work better for a finish coat in my situation? If the clear coat is best, do I need to apply a base coat (i.e. color) or can I get a good bond between the primer and clear without the base coat?

Thanks in advance for your help. John.

TGoodwin

Try some fine cut polishing compound on it. The 3M works good for me. You should be able to get a nice gloss if you have already hit it with 1500.

JohnW

My Feedback: (6)

Thanks, one step ahead. I ended up using PPG Deltron 3057 primer over the 282, wet sanded that up to 1500, then hit with two polishing compounds, the last one designed to remove haze. Was able to get a mirror finish even when looking straight on (perpendicular to surface.) Meguires #8 mold relase wax enhanced the shine even more. Stupid plug now won't stay put in the cradle as it is too slick. I had no idea primer would shine like that.

Ed Smith

If I may make a suggestion here. It is always an adventure when the time comes to remove the mold from the plug or, the first lay up from the mold. The compability of various paints, gelcoats and mold release does not seem to be an exact science. When the plug is finaly ready and all waxed up lay on a small patch somewhere using the exact mix of gelcoat and layups to see what happens. It is far easier to fix a small patch than have to tear the plug out in pieces and fix what is left. I do this at both stages, before I lay up the mold material and before the first lay up in the new mold.

However if you like adventure, plough right in!

Ed s

JohnW

My Feedback: (6)

Yes, I like adventure, but not the type Ed described. To date (knock on wood) I've never had a seriouly stuck plug or part. I've alwasy been able to break them loose without damage. But I am using a new wax (Meguires #8 mold release) because I can’t stand the Partall wax, and I am going to try a new process for first coat. I also would like to avoid needing to use release agents other than the wax for a better mold/part finish. Considering the time it took to make this specific plug, and the changes to my technique on this plug/mold, I will do some testing as Ed described before I commit to a full mold.

moldmaker

My Feedback: (5)

John W you are on the right track using Meguires wax best there is . I would use a very light mist coat of PVA . Just extra protection . My two cents worth

JohnW

My Feedback: (6)

I'm in heaven with the Megures #8. So easy to apply, and better yet, so easy to buff out. Runs circles around Partall for ease of use. I can't get PVA to spray and laydown to save my life. I have no clue what I'm doing wrong there. Seems to foam up an bubble. Too much air pressure? Maybe it can be reduced with water? What I have been using very recently is Price-Driscoll Epoxy Parfilm paintable mold release. Not exactly sure what it is, but acts similar to a silicon lubercant. Costs more than PVA, but a very light mist works and it is preloaded in a spray can... very easy to use and a little goes a long way. I'm considering using it when I make the mold, but it tends to fog the surface slightly, i.e. kills gloss. I will probably do several tests with/without release agents. I have a perfect spot on the chin cowl to do the tests, i.e. the surface is finished, polished, waxed, but wont be included in the mold/part, so if it is destroyed, no big deal.

RAPPTOR

My Feedback: (41)

HI I USED #8 ..PART STUCK SO BAD ,,JUNKED THE MOLD.. HI TEMP STUFF TOO!!

daven

My Feedback: (1)

After my stuck part thread maybe I'm not the guy to show how to lay down PVA, but I don't have a problem when I use it.

I dilute it 50/50 with water
Spray in my HVLP gun at 20 psi

The trick is an EXTREMELY light mist coat. It will look like tiny droplets all over the surface. DO NOT try to get the PVA to flow like paint.

After the first coat, wait about 10-15 minutes and do it again. I put down 3-4 coats like this, then paint. I have gotten very smooth parts out this way.

JohnW

My Feedback: (6)

Now I'm concerned with the stuck part and Meguires #8 as posted by rapptor. My test released just fine, and this was with six coats of wax, no PVA, etc. I really wanted to avoid any mold relase, like PVA, becasue it messes with the mold finish. Any more info on your stuck part in the mold with the #8?