By Joe - 2/13/2012 7:17:29 PM
Hey there,
I recently (today) demolded my first mold made using UniMold system (today). It turned out good.
I wanted to point some things people (especially newcomers) would want to know before they start working with it.
Facts:
Room T°: 19°C;
Gelcoat: 1 layer applied with brush; close to 1mm thick; 2% catalyst; time: 1 beer.
Coupling coat: 1 layer of 150 g/sqm; 2% catalyst; time: 1 beer but a bigger one.
Reinforcement: 5 layers of 450g/sqm; 2% catalyst; time: 2.5 hours (and no time for a beer).
Area of the plug: about 1sqm, many curves.
What I learned:
Applying the gelcoat and coupling coat was flawless.
But once I started the reinforcement side, it was another story. It all went good till third coat (on the 5 total). When beginning the third coat, i noticed the faster and faster time of resin gelling on the part. Yup, it was time for me to hurry (or reduce catalyst amount and/or room temp). Remember I used 2% catalyst and part has a "complex" shape which took time to wetout. I did not reduce catalyst amount, cos "Work in the morning and demold at night" is my moto.
Lucky me, and thats what i wanted to point for new users (or wanna-go-too-fast-guys like me): i really think bristle roller between each coat saved my mold integrity. Some would roll their mold after all the coats, some after 2 layers (i usually do that with non-filled resins), but keep in mind Unimold uses filled resin, which appears to me to be more difficult to "degas" and several layers of 450g/sqm mat dont help.
And yeah, dumb people like me have a god: it all went fine, finally. Final mold temperature was not at all excessive, even with 5 coats of mat and 2% catalyst. Unimold is a great process, I cant wait for my next mold. I hope this topic could help newcomers.
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By Matt (Staff) - 2/19/2012 5:26:54 PM
Great feedback guys. To be honest, the manufacturers to talk about lower catalyst ratios, particularly for the tooling resin (like 1-1.5%) and this is the ratio we have printed on the containers. We've actually this system to many times that we're probably a little bit cavalier with the catalyst and running it at 2% (like we did in the video) because we know how quickly we can put it down. Really though, there's no need to rush the tooling resin part, even if you wewre going for a gel it in the morning, coupling coat after lunch and lay it up in the evening (which is exactly what we did for the video) then the tooling resin layer is always going to cure over night and its exotherm will ensure that it cures in plenty of time.
The other thing to remember is that we mixed up about 3 or 4 batches of resin for the bonnet lamination. Even if the 1st or the 2nd layer is gelling off underneith as we're putty down the 4th layer it doesn't really matter providing the resin that we're laminating with isn't gelling off while you're using it.
I think we'll make it nice and obvious in the final edit that you should be running 1-1.5% catalyst unless you're doing something particuarly small.
All the best, Matt
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