By Griffsplace - 5/26/2020 3:58:12 PM
Hi
It all looked so easy, even and old idiot like me could do it.
First gave my part 6 layers of easylease, that seemed to go ok.
Mounted it up and barriered off for a flange.
First coat of tooling gel, mixed 100g with 2g mekp, seemed a bit thin, but seemed to go on ok. Second coat a couple of hours later, mixed the same the first batch but it went off very quickly and in about 10 mins had turned to gel
Picture is what it looked like a day later, its got so hot its deformed the plastic cup i mixed it in.
Ok wasnt too worried as i had 2 reasonable layers of gel coat. left it over night, Could not decide in the conflict of information between the bonnet video, where the gel oat is left to tack before the next stage, or overnight as per the datasheet. So it was left overnight.
I have come back to the job later the next day aftrnoon, temperature about 25 deg according to the thermomenter in the log cabin where i am working to attempt the coupling coat. Mixed up the same size batch 100g coat, 2g mekp, i am using new scales purchased with the kit, and this time, as much as i was sturggling to get the coupling coat and mat nicely stippled down with no bubbles ( the mat was coming apart. It might not be the easiest shape to mould as a first piece. once again the resign turned to jelly in about 10 minutes and got so hot i could not even touch the bottom of the cup.
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By MarkMK - 5/27/2020 6:51:40 AM
In warmer temperatures, using any sort of polyester resin/gel coat and be tricky, as reaction times can come down quite a lot. As you were using relatively small batches, though, it's quite surprising how quickly you were running out of time, but if you were struggling to get your matting down well it might have taken a little longer than expected
The lighter matting can be tricky to wet out well, especially on small and complex shapes. You might find it easier to cut it into smaller sections first, butting and slightly overlapping into corners, rather than trying to get a single piece to soak and conform. In this respect, the heavier mat will work better, as it soaks up a lot of the resin and becomes more pliable, but strategically placing smaller pieces should help a lot
It would likely be a good idea to use the Pattern coat primer/top coat to provide a reliable surface from which to mould, as it's known to be compatible and is relatively easy to finish once cured. Don't be too surprised if you sand through to the primer in some spots, especially on such a contoured piece, but a few sections where the surface is less glossy shouldn't be a big problem and the resultant mould can be compounded and polished-up afterwards. Having the part clear-coated is also an option, but without being certain if the finished part is sufficiently hardened or cured to offer a good release this might not be totally reliable
On a new pattern, I usually go with around eight coats of the chemical release agent, for a bit of added certainty and I usually apply this over a couple of days. You might still get a little bit of the coating coming away but, hopefully, nothing that you can't carefully remove with a blade or a little sanding.
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