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Dokomo
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Hi to all. It's my first mould using UniMould system. I follow exactly the tutorials and indications for making the mould. For the first step, i have bougth locally an MEKP catalyst ( i have attached the image ). I have applied a thin layer of gelcoat, and 4 hours later, another layer. After that, i have wait to the next day to let it cure, but the surprise was, that the part was totally ruined when i arrived next morning ( i have attached another image ). At that time, it had been drying for about 15h. The gelcoat has reacted with my part ( a motorcycle fuel tank ), producing great wrinkes all around the part. The tank was just finished, laquered and polished with PPG clear coat, and it has been drying for a week before I apply the gelcoat. The room temperature was about 17º in the day, and about 13º overnight. I have made a test yesterday, using 3 small mixes, one in 2%, another in 5% and a extreme one at 10%. The 2% mix, seems to never cure, it has been applied for about 20h right now, and keeps almost fresh. 5% looks nice, it's tacky in the surface and cured in the inside part, and the 10% mix its fully cured. I think the problem has been that the mixture at 2%, has react because it has been applied over the clear coat too much time without cure ( i look at it 6h after the application and it has no wrinkles at all ), producing the wrinkles at the end. The question is, it's safe to work at 5% ? Do you think that the problem it's another one ? Thanks in advance, and sorry about my english.
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thorstengsxr
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Hi
I use 1% to 2% MEKP if you want to make ist faster bild a smal heatbox I nefer used 5 % MEKP
regards Thorsten
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Shaneer22
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Make sure thats not your plug reacting with gel coat,don't use any 1k spray for plugs.make sure your not working in cold tempreture this time off year working in shed is a nightmare.
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Dravis
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MEKP is mots often diluted/thinned with something called Dimethyl phatalate, since concentrated MEKP is an explosive ...  The locally available MEKP you have is probably diluted much more than the ones Easy Composites normallly use. Different countries seem to have different laws regarding "deactivating" explosives. That will almost certainly mean other percentages than "normal" MEKP when added to polyesters as a catalyst. I think you should try to find out the correct percentage of YOUR catalyst to the "standard Polyesters" that are available locally. Your "local" MEKP could easily be diluted 5 times more than "standard" That being said: 17 degrees C. and 13 deg. C. at night is NOT enough for a proper cure of the EC Unimould system ... You need to have 18 -20 degrees as a minimum. Perfect example of "alligatoring" in that picture b.t.v.    
I'm pretty sure your "plug" needs a better coating and thicker waxing ... NO rattle can stuff, only 2- component paint, and still weeks curing at temps lower than 20 deg.
Good luck!!
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
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Dokomo
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Dravis (20/11/2014)
Your MEKP is diluted/thinned with something that I can not read what is ... Phatalate-something ...  That will almost certainly mean other percentages than "normal" MEKP I think you should try to find out the correct percentage of YOUR catalyst to the "normal Polyesters" that are available locally. Perfect example of "alligatoring" in that picture b.t.v. My MKEP it's diluted with phthalate, i've seen the composition in the specs of the MEKP that sells in easycomposites website, and seems to be the same. Today it's a little hotter than yesterday, near 21ºC inside the factory, and seems to have a big impact in the curing times too. Now i have to repaint, re-sand, re-do all the fuel tank and prepare it again for apply the gelcoat ....
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Warren (Staff)
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Unfortunately Dravis is right about the temperature and the issues with the plug surface.
You really need to be at 20C or above throughout the cure time.
The alligatoring is classic reaction by the gelcoat to a surface it doesnt like.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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Dokomo
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Warren (Staff) (20/11/2014)
Unfortunately Dravis is right about the temperature and the issues with the plug surface.
You really need to be at 20C or above throughout the cure time.
The alligatoring is classic reaction by the gelcoat to a surface it doesnt like. The fuel tank surface its a PPG clear coat, tipically used in a lot of vehicles. In the test i made yesterday, there were no problem, because it has cured "in time". I think the problem was that it doesnt cure, and more than 12 hours over the clear coat has cause the reaction. Warren, it's the phtalate contained in the MEKP i used a problem or it doesnt matter ?
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Dokomo
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By the way, forgot to mention, thanks to all for the quick and good answers, its a pleasure to post here ! 
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brainfart
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Since it was way too cold the first layer didn't cure enough and the second application caused the alligatoring/orange peel look by redissolving the first layer.
20°C is the absolute minimum, I wouldn't use it at temperatures below that.
I doubt that the concentration of your catalyst is much different than the stuff available in other countries, and dimethylphtalate is a common phlegmatizer used for peroxide catalysts, it won't cause any problems
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Dravis
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According to my old books from my time building glass-fibre/polyester boat hulls, the actual content of MEKP itself in the "catalysts" can vary from 40% and up to 80% Since the MEKP is just a catalyst, the percentage of catalyst to resin is not very critical, but a combination of only half the expected "actual" percentage of MEKP catalyst AND temperatures that are really a bit too low, and the problem will show its ugly alligatored face ...
"Sapere Aude"... Dare to KNOW! The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind... 103% of all people do not understand statistics... Do not adjust our mind, theres a fault in reality :-)
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