how do you complete your molds?

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how do you complete your molds?

Author	Message
67redrocket	67redrocket posted 10 Years Ago HOT Topic Details
Group: Forum Members Posts: 49, Visits: 486	I have made smaller moulds with the epoxy tooling gelcoat and epoxy putty. I have experienced that its easyest to put the hole mould in a bag and then do the infusion. But my question is what you do to complete the mould, do you put anything on the back of the mould to ensure that there is no sharpe dges to puncture the vacuum bag?
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Ronny	Ronny posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 58, Visits: 401	I had to do the same thing with one of my moulds. I placed breather fabric on the backside, as it came along with the infusion starter kit i believe.
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Hanaldo	Hanaldo posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	I always smooth the back of the mould off. If you aren't confident to rub the back of the mould with your hand without getting pinned, then envelope bagging isn't a good idea. Just a quick but thorough rub up with 120 grit will do the job. Breather works too, but I only ever use it if I'm double bagging and the stuff isn't going to get saturated with resin. Not only does breather soaked with cured resin make your mould a real pain in the ass to use; it can also destroy the part you're doing if it saps out more resin than you can afford, leaving dry spots. Which is easily done. A better option if you can't smooth off the mould is to use release film or a piece of vacuum bag. This can at least be peeled off, won't absorb resin, and still gives a decent amount of protection.
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Ronny	Ronny posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 58, Visits: 401	Listen to Hanaldo
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Dravis	Dravis posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 592, Visits: 1.9K	Yup -- listen to Hanaldo .. I always smooth off the outside of my moulds .. then I coat them whit a layer of laminating resin - (Especially the "putty" moulds) that way they mostly become perfectly vacuum tight .. Leak free .. I have one or two that are not "leak-proof", and have too narrow flanges, and what I do to stop the resin flowing to the back, is to add gum strip all around the "too narrow" flange .. I leave the white backing tape/paper on, so the envelope bag can slide on the gum -- to avoid bridging on the part .. "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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FLD	FLD posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 2.7K	Same here for smoothing the back side over. If you really want to go to town you could use some flowcoat for a nice smooth finish.
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Zebra	Zebra posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 14, Visits: 32	I use Vaseline to smooth the rear side of epoxy putty molds before it is dry. It creates a very smooth finish. I know... Vaseline..... Is there anything it can't do!
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Hanaldo	Hanaldo posted 9 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	I'm guessing you don't make boats Zebra?
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*VVS*	*VVS* posted 9 Years Ago HOT Post Details
Group: Moderators Posts: 226, Visits: 334	Bad idea using breather cloth on the reverse side it sucks up resin of you get any flow to the back side and then once cured is worse than the original csm/putty. best to tidy the edges and flange well, make sure you lay up well at the edges when making the mould so you get a good mould as you may want to gum tape close to the edge and can then get leaks through the edge. If you don't want to sand all the back you can get good results sticking ducting tape over it, this can be removed and renewed if and when.
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