I am rather crushed after having some plugs stick in new moulds I was making (a new Scratcho nose cone mould and a single Stratos stab mould). The stickup was only on one side, and it was the second half that was done.

These were epoxied glass parts for the plugs. Painted with 2-pack primer and black topcoat. Sanded and filled and repainted till smooth, then wet sanded and polished to mirror perfection.

I am using Frekote 700NC mould release. The gelcoat is Rengel SW10. Cured for 4 days at 35 deg C.

On both moulds, the side that was gelcoated/ built up first, released absolutely, 100% perfectly ... plugs virtually fell out of the moulds on that side but the other side is 98% paint stuck very hard. I had to destroy both plugs to get them out

A bit of history … for a year or so I’ve been using some stuff that a friend got from a friend, just a sample which he gave me as “Frekote”. It has worked flawlessly and I have become a total Frekote convert. I ran out of the sample and have been chasing up more and with difficulty I finally got a tin of Frekote 700-NC which is the proper epoxy release product. Coincidentally, my friend managed to get the original tin of the stuff I’ve been using and it’s actually Frewax, which is a product containing the Frekote polyester release, with some wax.

I used the 700-NC on these moulds. The only differences I can think of in the process used for the first (successful) half and the second (stuck) half were these:

1) I used the Frekote FMS mould sealer on the first half. After using it, it was hard to buff the plug back to gloss. And I’d been told that it doesn’t aid the release but is more of a protector of the mould, to be used on the new moulds. So I didn’t apply it to the second half of these moulds.

2) The first half, I applied Frekote, let it dry then polished it back before wiping on the next coat. A tech guy advised me that you shouldn't buff it off between coats. So on the second half I did the very thin coats as advised, but just wiped the next coat straight over the top. Only one buff at the end to gloss up the plug.

It's hard to take, not being sure what has caused such a radically different result and at the moment I feel like completely giving up. However I spent an hour or so "gently" chipping and scraping it out with chisels etc. and am gradually getting the paint off the nose cone plug, but scratching the gelcoat a bit in the process. But with some work, I hope to be able to salvage the moulds.

Any advice/ suggestions??

Sorry to ask the obvious but how long did you let the Frekote set before doing your layup? I've had similar plug-damaging results when I didn't wait long enough (typically 30 minutes for a pretty heavy spray of the stuff). I'm not using gelcoat in my layups so that is one difference.

I've also started spraying a second coat without buffing in between and have had good releases.

Not a lot of meat there but maybe something to try,

Mike

I did 7 coats of Frekote, not the spray but the liquid. It was completely dry before each next coat.

When I used Frekote I polished between layers, used the sealer and had no problems when making the molds.
You can pour some chemical paint remover, it will atack the paint and make it easier to remove with less scratch to your molds. I did it this way once and the mold did not suffer badly. I applied the paint remover with a brush so it wouldn't attack the already clean mold surface and with a piece of hard wood, was able to remove the paint. It doens' magically solve, just soften enough. It was 2k car paint.

Wow. I never thought paint remover would work on 2k paint! Wish I'd waited and tried that before scratching up my mould.

AvB-

To be clear:
The side that you DID you FMS sealer on did not stick.

We see a big difference in how the Freekote works when used in conjunction with the FMS. The 700NC is a release interface but it is not a barrier( like PVA etc.). The mold surface if left with only Freekote 700NC is more prone to sticking than with the sealer. This is especially true of composite tools.
The sealer acts as a stable substrate for the releasing interface, as you noted, the good side parts fell out. Controlling the amount of release is a bit more tricky when using sealer if you want limited release(different topic).

I used to think sealer was a nice to have, no I think it is a NEED to have. This is true even on steel tools.
Scott

I just began using Freekote a month ago, and I have to say that with using the FMS & 770NC together, I am having great luck. So much faster than wax & PVA, and the parts & plugs release VERY easily. I have been doing 3 wipe downs with the FMS (wipe on & then wipe off prior to the part drying) 10 minutes apart followed by 3 coats of 770NC (wipe on & then wipe off prior to the part drying) 10 minutes apart.

The whole sealing & release application for plugs or new molds takes basically 1 hour (apposed to most of the day for wax & PVA) and look as slick as the painted master plug. I have made 5 new molds in the past month and am a believer!!

Best wishes,

Scott Smith
NMPRA District 7 YP
SEMPRA President

Whoever told you that the FMS doesn't aid in the release gave you bad information. I always use the sealer when prepping plugs and molds.

If I was in your position I would try to reconstruct the problem. I'd shot a scrap with you plug paint and let it cure. Then I'd apply the sealer to one half of the sample and apply the release to the whole sample. Then do a simple layup with your gel-coat and a molding resin on the sample. Let it cure and peel it off. If the side without the sealer sticks then you know that not using the sealer is the issue.

While doing this experiment may seem troublesome, at least you will know what the problem was and choose differently in the future.

I apply the Frekote system just like ScorpionRacing and see no degradation in the quality of the plug or mold finish. I never buff the surfaces unless I'm just trying to remove finger prints, dust, and such.

Hey that's fantastic, thanks very much for that advice guys. I am kicking myself for not using the sealer on the 2nd half. If I can ever regain enough motivation to try again I think I'll get it right next time!

Also thanks for the advice on the wiping on method. I am prone to hearing new advice from someone and modifying what I do, even when what I've been doing is working fine, and then having problems. This was a case in point. Not only with the advice about the sealer but also the application method. The guy who first gave me the sample said "wipe it on, wipe it off (still wet), leave half an hour, repeat 4 times". That's what I did (making parts in my used moulds) but then recently I was told to let it dry, and wipe the new layer over the top and I changed to doing that.

So I want to get this crystal clear ... tell me if I"m wrong. Firstly for new plugs/ moulds, use the FMS sealer 3 times at the start. The method of application for the FMS and the Frekote is the same. You wipe it on thin, then within a minute or so before it's dried, you wipe it off with a dry cloth. Don't buff it, just wipe it dry. Wait 10 mins, then repeat. At the end if there are streaks etc on the gloss surface, give it the minimum polishing with a dry soft cloth.

Is that right?

Originally Posted by AvB

So I want to get this crystal clear ... tell me if I"m wrong. Firstly for new plugs/ moulds, use the FMS sealer 3 times at the start. The method of application for the FMS and the Frekote is the same. You wipe it on thin, then within a minute or so before it's dried, you wipe it off with a dry cloth. Don't buff it, just wipe it dry. Wait 10 mins, then repeat. At the end if there are streaks etc on the gloss surface, give it the minimum polishing with a dry soft cloth.

I follow the Frekote instructions for applying the FMS sealer. I liberally wet the surface with a rag, wait 15 or 20 seconds (or when I notice edges start to evaporate), and wipe the excess off with light pressure. I apply 3 applications of the FMS sealer waiting 15 minutes between applications and wait 15-20 minutes after the last application.

I deviate when applying the 770-nc release (never used 700). The instructions make no mention of wiping it off after applying. This will often make the mold hazy and it will really build up after lots of application cycles. I end up applying it just like the FMS sealer. I wipe it on and wipe if off when I notice any of the edges start to evaporate. I wait 10 minutes between the 3 applications for new surfaces. When the mold is fully seasoned and releasing well, I wipe it off with a rag in my left while I apply it with the right hand. I've found that I need to add it every cycle with many fuselage molds. Sometime I can apply it every other molding cycle. On simple shape like canopies and some wings I've got as far as 5 cycles before reapply.

Yes, that is how I have been doing it. Wipe it on, and right back off BEFORE it dries. In my case, I wipe it off within 10~15 seconds or it will streak on me. I make sure there are no streaks before letting it set for the 10 minutes. If there is any streak that remain after the wipe down, I wipe the spot with the FMS or 770NC (whichever I am currently applying) and buff it right off. You don't want a dull spot to remain, or it will not come out easily after it dries for the 10 minutes.

Scott Smith
NMPRA District 7 VP
SEMPRA President

Thank you VERY much guys. It would have been smart of me to ask for this advice earlier! But I hope some others benefit from it too.

Originally Posted by wyowindworks

If I was in your position I would try to reconstruct the problem. I'd shot a scrap with you plug paint and let it cure. Then I'd apply the sealer to one half of the sample and apply the release to the whole sample. Then do a simple layup with your gel-coat and a molding resin on the sample. Let it cure and peel it off. If the side without the sealer sticks then you know that not using the sealer is the issue.

This is very good advice! However, it takes a bit of effort but it will tell you where you're going wrong in all likelyhood.

New plugs and new moulds are always much riskier than seasoned moulds, They are prone to outgassing, porosity, lack of complete cure etc. If there's any stage of mouldmaking to take great care with it's new moulds!

Don't give up! It's not an easy thing to learn, but the payback in personal gratification is well worth it!

I was really bummed today... a Scratcho stab and fin that I laid up yesterday and PU filled this morning ... broke the moulds open and the paint had stuck very badly and the parts were stuffed.

But once again, it's my own fault probably, from cutting corners. These are quite well seasoned used moulds that were used with wax maybe 5 times, and with Frekote also probably 5 times. Nothing has ever stuck up in these moulds. I was using the same paint and the same epoxy resin as previously. Yesterday, before using them, I gave the moulds a rubover with Farecla G3 polish to clean off some slight roughness building up. After that I gave them 4 good wipes with Frekote 700NC. I guess the polish took off the sealed micro surface and I should have done the Frekote sealer treatment again. Do you guys agree?

But ... I am feeling rather chuffed ... I have worked out a quick fix! I thought darn, I'm not gonna spend many hours chipping away and damaging the moulds like last time. I remembered the guy mentioning using paint stripper and I probably would have tried it but I don't have any and the shops are closed. I tried wetting the paint with paint thinners and although it remained stuck hard, I thought it was maybe a bit easier to chip/ scrape off.

So I flooded the mould surface with thinners, laid a patch of paper towel over that to soak up some of the thinners, then laid a sheet of laminating film over that and put the other half of the mould on top, to press the plastic flat and keep it all shut tight. Ten minutes later, I was able to shave the paint off quite easily with a paint scraper knife, without damaging the mould. So good!

This is an annoying glitch but on the plus side I have to say it's not taking me too long to paint, lay up, vac bag, and PU fill the tails. So it's not a huge deal. Just an hour or so of depression and wanting to quit building, instead of days.

If you ever polish a mold you will strip off any release and sealer. When reapplying a semi-permanent system you want reapply the whole system......this would include the sealer.

I would be concerned that you are getting a "slight roughness build-up" on the mold surface. This shouldn't be happening. If you are getting bits stuck to the mold surface then the mold will get increasing reactive until it sticks.