Soaring Steve

OK... I have made a few molds in the past with mixed results. I am currently building a Extra 3.25 and made the plug for the cowling from styrofoam, glassed it, filled, sanded and got it to a point were it was pretty smooth and acceptable. I clear coated the primer (Duplicolor filler / primer) with Acrylic Enamel, wet sanded till smooth and glossy. I went ahead to make the mold, applied approx 10 coats of meguirs #8 mold release wax. I was so slick that I was having trouble holding it. Anyways, made the mold and I couldnt seperate the halves. I finally just melted out the foam and tried to peel the layer of glass from the inside of the mold and all the paint, primer and glass stuck to the inside of the mold. Ive been trying to save this mold but I dont think I can. I need to start over It took a week just to get the last plug right. Why did it stick?

Any suggestions so I dont have to repeat this process for a third time? [8D]

Thanks!

Steven

wyowindworks

You probably had some chemical interaction between the paint and the resin. Wax, no matter how many coats you apply, is unable to block reactivity between the plug/mold surface and the fresh resin used to make the mold/part. PVA (polyvinyl alcohol) could have been used to block this reactivity. The purpose of using PVA is to create a barrier between the plug/mold surface and the fresh resin. Wax provides slip. PVA blocks reactivity. If you don't want to use PVA you need to do lots of testing with plug surfacing agents and your resins to make sure that no reactivity will occur.

BTW, the first coat of wax provides the most build up. Subsequent layers of wax are about 1/20 of the thickness of the first coat. I usually only use 4 coats of wax + PVA. In theory you only need 1 coat of wax. The reason most manufacturers recommend 3 to 5 applications is to insure complete coverage.

Soaring Steve

Thanks..

Ive had this problem in the past with plugs sticking, but never this bad.

I could'nt find any PVA locally here in the stores and I cant order it online (trying to keep this off the wifes radar ). Would a primer with something other than a laquer base be more stable? Ive tried to locate PVA at stores like Michaels in their sculpting section, but didn't see any there and the auto body shops here locally don't have it either. does it go by any other name or is there a recipe to make some at home?

Steven

wyowindworks

Any paint can be problematic. Sometimes not letting them cure long enough can exacerbate the problem. Usually the safest paints are catalyzed urethane automotive paints. They will require spray equipment and $$$$. I prep all my plugs with PPG Deltron DC3000. It works well with wax/PVA and semi-permanent systems like Frekote and dries in 2 hours. It's really nice stuff.
I don't think you can make PVA at home. Any attempts to will surely arouse your wife's suspicion.

I have heard of people using hair spray in place of PVA. I've personally never tried it, but some testing could definitely be done. Here is an article about using hair spray

PVA is pretty cheap stuff. SEE HERE for Partall Film #10 (PVA)

PVA will bead-up like mad on Meguiars release waxes making it difficult to apply. If I'm going to use wax & PVA, I like to use Part-all Paste #2 (wax) and Part-all Film #10 (PVA). These two products play very nice together.

SCALECRAFT

My Feedback: (13)

I use the same primer exactly. Wet sand and wax. 3 coats partall wax and one thin layer PVA. Never have problems.

The only question is why did you put an enamel clear coat. The wax will make the wet sanded primer even shine??

PVA is available at S&W plastics these days.

Steve

Magne

I have experienced similar problems before when painting the plug with single component (rattlecan) paints. Went to two component automotive paints, and problem solved.
I am almost certain that there is where your problem lies.

Magne

JÖRÖ

Using hair spray is  easy and result for me have been better than PVA. 1st 3-4 coats simoniz carnauba wax. Then hair spray lightly wipe it lightly with cloth. This eliminates tension of hairspray surface. Spray streight away thicker layer hair spray. Not too much it will drain. Let it try. this have been worked perfetly for me. Easy put on wax, using low price extra hold huge cans.

Cheers

Jörö

Soaring Steve

Ok.. Sorry its been so long since I last posted, but Ive made a new plug (which is actually better than the first one) and its taken me a while. I constructed the base from styrofoam, covered with 2 oz cloth with West epoxy.. Ive sanded, Ive sanded, filled all the holes and Im pretty happy with it. Its now in primer (Duplicolor filler / primer). My question is this: Can I just clear coat the primer like I did last time. which didnt turn out so well, or should I paint it and clear? I do plan to use PVA this time along with the wax.. Im just a bit nervous since Ive put much time into this that I dont want another stuck plug. I did read the article on the West Systems web site about the hair spray, but was feeling a bit uneasy about trying something so different and not having it work. I does seem like a good alternative tho, and its available where as I will have to order a gallon of PVA and never use half of it in the rest my life!

I do have some automotive 2 part clear that I am thinking of using. I also think that the rattle can stuff was a part of the original problem as well.
[img][/img]

Thanks for all your help guys!

Steven

wyowindworks

Steven, why don't you test it? Shot your paints on a sample, apply the wax + PVA, and perform a little layup with your resin and see how it releases.

Soaring Steve

Wyo-

I think that will be a good idea. I have the ABS wheel pants that I had purchased years ago from Rich Uravitch, which are all primed and ready to go.. I was considering redoing them in F/G anyways.

I think that on one pant I will try the hairspray, and on the other Ill try the PVA and do a comparison and let you know which works better for me. I try it out on the wheel pants before I sacrifice my new cowl plug..

Soaring Steve

Ok.. I found some PVA at a local boat repair center. He was kind enough to give me a water bottle full of it for free.

So the new plug was made, waxed 5 times throughly, sprayed with 3 coats of PVA, which flowed out nicely.

So I laid up the mold on the new plug and Ill be damned, it didnt stick! WoooHooo! It really came out nice. The nicest mold I have yet made.

Its amazing what will happen when you get the right materials.......

Steven

wyowindworks

WooHoo! Good to hear.