Orange Tooling Gel issue

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#1

I’ve been messing with making some moulds. I’m going to list what issues I’ve had with each and what I learned.

All these processes have used at least 3x coats of dolphin wax and pva

  1. First mould was of a small plastic tray. I poured the orange tooling gel on and it was extremely thick in some spots. In the end the item melted underneath because I think I either over catalyzed or just put to thick a coat on. I did not have lifting issues with my tooling gel and I wiped my pva on with a rag

  2. Second mould was a larger tray. I sprayed my pva on with a hvlp gun, I put about 2 heavy coats on. After that I put my orange tooling gel on but not nearly as thick. after my tooling gel cured I had lifting issues on my flat surfaces. I fixed this by vacuum bagging my first two layers of csm.

  3. My third mould was a bracket. Besides for it getting channel lock, I had the same issue with the flanges and flat surface spans lifting up before I can reinforce them.

I work in a 70 degree room that sometimes drops to around 60f. I put my chop strand mat on 2 layers at a time sometimes but this seems to be an issue before I even get the chance to overheat with those layers with poly resin.

Anyone else have this issue of your orange tooling gel lifting off your part? I’m thinking either I’m putting to much pva on, or I just need to wax less so there’s less release. It generally happens on flat surfaces and the only reason I ask is because I’m making a mould of a semi flat panel in the next few days.

#2

What type of tool gel coat are you using and how are you applying it? Most gel coats are meant to be sprayed with a wet thickness of approximately 20 mils (0.020 in), be sure to check with a mil gauge. Be sure to follow the manufacturer’s instructions as they vary from mfg to mfg and gel coat to gel coat.

#3

I’ve been using tooling gel from fibreglast.com. The next piece coming up though I bought orange tooling gel from Ill street composites since it’s half the price.

Mekp hardener doesn’t vary does it?

Also I’ve been brushing it on but others haven’t had this issue before?

20 mils is pretty thin right? That’s actually very thin compared to some of the places on my mould. Is it possible that I just put it on to thick and this is causing the issue?

#4

How thick is your thick and what percentage catalyst are you adding? It does sound from your discription like you are putting it on thick or over catalyzed, did it take long to go off what did you use to measure out? You also need to brush out the gel coat dont just pour or roll it on as air can be trapped brush it out as well, just like you would a paint.

You should also have no problem applying by hand with a roller/brush. Try two thinner coats rather than one thick. Tooling gel can come for hand application as well as spray, further good results can still be achieved applying spray gel by hand.

Regarding overlaying I always do one layer csm let it go off ,then two at a time after .
We really need to know what percentages mekp you are using as it should be possible to reduce them for laying up or change over to a slower catalyst for more working time.

Polyester can melt some plastics by the way.

#5

There are possibly as many types of MEKP as there are resins but the most common has 9% active oxygen (MEKP-9 or DDM-9). 20 mils (0.020in) is fairly thin, roughly 5 sheets of printer paper. Besides the proper initiator in the correct amount, thickness is the most important thing to get right. Fiberglast sells mil gauges which they call a “gel coat thickness gauge” PN: 122-A, this is a necessity if you are going to apply gel coat.

#6

Ok awesome. All great information. I’m going to say that I had some spots thicker than others ranging from 1/32 and 1/4 on the flat portions. For first two moulds I listed I added 2% mekp but the last item I only used 1%. Both lifted up around flat areas so that why I was confused. I used the same gel coat from fibreglast and their mekp but on the last mould I used ill streets.

I’ll pay closer attention to keeping my coats even this time around and going slightly thinner when brushing. Nobody else has had this issue before though?

#7

1/4inch? That is WAY too thick, and will shrink and deform. Just like you witnessed.

#8

Still having some issues

My next mould I applied by brush. Cheap bristle brushes that didn’t go on too smooth. I again had lifting issues where I had some curves where my clay met my mirror on turns. I didn’t notice it to much the first coat but 2 1/2 hours later in 70 degree weather it was lifting. I still out a 2nd coat on and the next morning it was bad.

After that failed attempt I tried foam brushes. I redid my mould and decided to not use pva this time. The plug is fairly simple so I’m not worried. I added 2% mekp to my illstreet orange tooling gel and brushed on a light coat. It was as even as I could get it. I din’t have a gauge but in some spots you could still see the mirror and plug.

Is that too thin? Or should I have gone thicker and just did 1 coat? Fast forward a nap and 4 1/2 hours later. I come back to my plug and I put another coat on with my foam brushes and instantly see alligatoring in some places. Same thickness I tried for as well. You can barely see the mirror and plug. 95% of it is covered and all you can see is orange.

If I do 2 layers of gel do I wait until fully cured? Like 24 hour wait? This is semi frustrating. Any suggestions? I stopped the pva because I didn’t want lifting issues even though in an ideal world that wouldn’t happen. Now I have alligatoring but may still have lift issues. I’ll have to see when I wake up.

#9

Lifting happens because of the shrinkage of the polyesther or vinylesther gelcoat. Thin layers should help and pay attention that the do not become to hot. Keeo them cool and let it cure slow. That might help.

#10

I think you need to get a mil gauge to measure the wet film thickness of the gel coat as you apply it. It is very important to have the proper thickness because too thin and too thick will cause problems like you are experiencing. I would apply 1 coat at 18 - 25 mils (0.018 - 0.025 inches) and after the gel coat cures to a point where you can touch lightly with your finger and none transfers to your finger i would hand laminate a 1.5 - 3.0 oz chopped strand mat skin coat this should help with the pre-releasing of the gelcoat as well.

#11

Yeah I thought it was to thick of layers, but now I did a thin layer and then another and still have issues, alligatoring. I’m guessing fmthese are separate issues though. Lifting and alligatoring that is.

The times I’ve done 2 coats I’ve always waited until tacky but none transfers onto your finger. So I’m still wondering.

The first time on this one mould where I had issues with lifting but not alligaoring I’m not sure if I let my pva dry 100%. When I lifted up the entire tooling gel the next morning there was one spot that seemed like it didn’t dry all the way, so I know that was probably an issue too but it still lifted in other spots.

Has anyone just let every layer cure individually before adding another layer? I mean it’s poly tooling gel and poly resin so II stays semi tacky anyways.

#12

Gelcoat stays semi-tacky.

The alligatoring is undercure, so too thin layers, or too low temperature.

I am surprised the gelcoat prereleases at the right thickness.

#13

It was prereleasing from the concavness and those curves were harder to get an even coat because of the cheap bristle brushes I was using before. Foam brushes work do much better.

I didn’t have lifting issues on the mould I’m working on now, just alligatoring in certain areas and thank god non on the mould itself. Just the flange area. I’m going to glass like normal and hopefully pull some parts next week.