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Massimiliano
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Hi, Please see pics below of the mould and the part after infusion. The mould has been applied 6 passes of easylease, 1 pass of wax and 1 mist of pva before laying fabrics. All the timing between passes has been respected, and pva was left overnight to dry. Composite spray glue from ec has been used to keep the fabric in place. When it came to extract the part, some small areas detached as they should fine but the majority had the gelcoat stuck on it, as visible in the pic. I was afraid of a long sanding job but tried first with a chisel and small strokes and with much relief chips by chips all the stuck gelcoat came away with leaving a glossy part surface. My questions is: - what could be the reasons why the gelcoat was so adhered (I use adhered and not bonded because with some mechanical force the gelcoat separated) to the part?  
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Massimiliano
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Group: Forum Members
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+xHi, Please see pics below of the mould and the part after infusion. The mould has been applied 6 passes of easylease, 1 pass of wax and 1 mist of pva before laying fabrics. All the timing between passes has been respected, and pva was left overnight to dry. Composite spray glue from ec has been used to keep the fabric in place. When it came to extract the part, some small areas detached as they should fine but the majority had the gelcoat stuck on it, as visible in the pic. I was afraid of a long sanding job but tried first with a chisel and small strokes and with much relief chips by chips all the stuck gelcoat came away with leaving a glossy part surface. My questions is: - what could be the reasons why the gelcoat was so adhered (I use adhered and not bonded because with some mechanical force the gelcoat separated) to the part? By further thinking about the whole process I think the only explanation could be the spray adhesive. Maybe the solvent in it dissolved the pva and the release agents. For the next part I would like to avoid that spray adhesive, what do you use to keep the fabric layers firm, especially in tight corners etc?
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Hanaldo
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No, that won't be the issue. I haven't got time to reply in full just now, but it certainly isn't a spray adhesive issue. I'll try to reply properly in a few hours.
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Massimiliano
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+xNo, that won't be the issue. I haven't got time to reply in full just now, but it certainly isn't a spray adhesive issue. I'll try to reply properly in a few hours. Can't wait to read your post!
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Hanaldo
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Ok, so - you havent really experienced a release failure here, atleast not a total one. If your release hadn't worked at all, you wouldn't have been able to remove the gelcoat afterwards at all, so the fact you were able to remove the gelcoat and leave a glossy surface tells me the release agent did its job. When you have a release failure, it is absolutely impossible to remove the gelcoat.
So what's happened here is a total adhesion failure between the substrate and the tooling gelcoat, which is somewhat more strange. The fact there was more adhesion between the released surface of the gelcoat and the carbon part than there was between the tooling gelcoat and the reinforcement is concerning. What did you make the mould from and how did you lay it up, what was your process?
You may have had a partial release failure as well, where the release agent worked well enough to not allow the epoxy to bond to the gelcoat but not well enough to allow a very easy removal. But the fact the gelcoat came away from the mould reinforcement means that is what actually failed, and the tension between the epoxy and the gelcoat only aided in pulling the gelcoat off the mould easier.
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Massimiliano
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Group: Forum Members
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+xOk, so - you havent really experienced a release failure here, atleast not a total one. If your release hadn't worked at all, you wouldn't have been able to remove the gelcoat afterwards at all, so the fact you were able to remove the gelcoat and leave a glossy surface tells me the release agent did its job. When you have a release failure, it is absolutely impossible to remove the gelcoat. So what's happened here is a total adhesion failure between the substrate and the tooling gelcoat, which is somewhat more strange. The fact there was more adhesion between the released surface of the gelcoat and the carbon part than there was between the tooling gelcoat and the reinforcement is concerning. What did you make the mould from and how did you lay it up, what was your process? You may have had a partial release failure as well, where the release agent worked well enough to not allow the epoxy to bond to the gelcoat but not well enough to allow a very easy removal. But the fact the gelcoat came away from the mould reinforcement means that is what actually failed, and the tension between the epoxy and the gelcoat only aided in pulling the gelcoat off the mould easier. Thank you Hanaldo, I can't thank you enough for the sustained support you offer in this forum! The mould has been made with epoxy tooling gelcoat (a new epoxy tooling gelcoat never used before) and laminated with glass and laminating epoxy. I laminated the glass when the tooling gelcoat was already full cured. For sure I will never use again thos products, and luckily Ec resumed shipping to the EU. Now I have another mould made in same way and I need to pull another one part from it and I fear to have same issue. What would your recommend to favor a release?
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Lester Populaire
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+x+xOk, so - you havent really experienced a release failure here, atleast not a total one. If your release hadn't worked at all, you wouldn't have been able to remove the gelcoat afterwards at all, so the fact you were able to remove the gelcoat and leave a glossy surface tells me the release agent did its job. When you have a release failure, it is absolutely impossible to remove the gelcoat. So what's happened here is a total adhesion failure between the substrate and the tooling gelcoat, which is somewhat more strange. The fact there was more adhesion between the released surface of the gelcoat and the carbon part than there was between the tooling gelcoat and the reinforcement is concerning. What did you make the mould from and how did you lay it up, what was your process? You may have had a partial release failure as well, where the release agent worked well enough to not allow the epoxy to bond to the gelcoat but not well enough to allow a very easy removal. But the fact the gelcoat came away from the mould reinforcement means that is what actually failed, and the tension between the epoxy and the gelcoat only aided in pulling the gelcoat off the mould easier. Thank you Hanaldo, I can't thank you enough for the sustained support you offer in this forum! The mould has been made with epoxy tooling gelcoat (a new epoxy tooling gelcoat never used before) and laminated with glass and laminating epoxy. I laminated the glass when the tooling gelcoat was already full cured. For sure I will never use again thos products, and luckily Ec resumed shipping to the EU. Now I have another mould made in same way and I need to pull another one part from it and I fear to have same issue. What would your recommend to favor a release? It's best practice to work wet in wet, so laminate the reinforcement once the gel coat is firm but still tacky. I learnt to sprinkle chopped glass fibres into the gel coat to improve bonding between the layers as well. I honestly don't know how much this helps, but i never had an issue with gel coat flaking off
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Hanaldo
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Yeh I suspected as much - epoxy moulds can be so tricky compared to styrene based moulds. You really really need to get that bond window right, and some epoxies can be extremely unforgiving if you dont get it right.
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Massimiliano
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Group: Forum Members
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+x+x+xOk, so - you havent really experienced a release failure here, atleast not a total one. If your release hadn't worked at all, you wouldn't have been able to remove the gelcoat afterwards at all, so the fact you were able to remove the gelcoat and leave a glossy surface tells me the release agent did its job. When you have a release failure, it is absolutely impossible to remove the gelcoat. So what's happened here is a total adhesion failure between the substrate and the tooling gelcoat, which is somewhat more strange. The fact there was more adhesion between the released surface of the gelcoat and the carbon part than there was between the tooling gelcoat and the reinforcement is concerning. What did you make the mould from and how did you lay it up, what was your process? You may have had a partial release failure as well, where the release agent worked well enough to not allow the epoxy to bond to the gelcoat but not well enough to allow a very easy removal. But the fact the gelcoat came away from the mould reinforcement means that is what actually failed, and the tension between the epoxy and the gelcoat only aided in pulling the gelcoat off the mould easier. Thank you Hanaldo, I can't thank you enough for the sustained support you offer in this forum! The mould has been made with epoxy tooling gelcoat (a new epoxy tooling gelcoat never used before) and laminated with glass and laminating epoxy. I laminated the glass when the tooling gelcoat was already full cured. For sure I will never use again thos products, and luckily Ec resumed shipping to the EU. Now I have another mould made in same way and I need to pull another one part from it and I fear to have same issue. What would your recommend to favor a release? It's best practice to work wet in wet, so laminate the reinforcement once the gel coat is firm but still tacky. I learnt to sprinkle chopped glass fibres into the gel coat to improve bonding between the layers as well. I honestly don't know how much this helps, but i never had an issue with gel coat flaking off For this second mold just after having applied the epoxy gelcoat I covered it with microfibers. Once cured, I vacuumed the fibers and the gelcoat has been left sort of "hairy". I did that to favor the bond between the gelcoat and the reinforcement.
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Hanaldo
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Thats ok, but it is still only a mechanical bond. Ideally you want a chemical bond for maximum strength, which means getting the bond window timing right.
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