Carbon and resin not taken to gel coat

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Carbon and resin not taken to gel coat

Author	Message
Howie7	Howie7 posted 10 Years Ago HOT Topic Details
Group: Forum Members Posts: 1, Visits: 17	Hi everyone, first post on here. I have a small background doing some fibreglass repairs and mould making so have a slight clue about what I'm doing. But obviously not too good as I'm having a nightmare here. Recently got myself some carbon and making some small stuff and decided to take on the rather ambitious task of taking a mold of the splitter from my car (Honda civic type r ep3) and making a cf replacement. First time round making the mould I used easy composites tooling gel coat followed by resin and a fair few layers of csm. When I tried to release it the gel coat had taken to the bumper and the csm and resin was separate from it. Absolute nightmare so stripped it all off and started from scratch and my mould was complete without a hitch. After that I gave the bumper 2 coats of wax and 2 coats of clear gel coat. I ran out of time and had to leave it 4 days because of work. Then I gave it a coat of resin followed by 2 full layers of cf mat and some reinforcement cf around the edges with finally some honeycomb core material in the centre for extra strength. I gave it 24 hours to cure and when I tried to release it the same thing has happened as what happened with the first mould and the gel has taken to the mould leaving it basically stuck in the mould. I have tried to get it released but it's just releasing between the gel and the cf/resin. I'm aware albeit slightly disheartened that I have made a booboo and wasted a fair amount of material. But I am more so concerned about where I went wrong and how to ensure this doesn't happen again. Thanks in advance for any advice or help, thoroughly appreciated Howie.
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Fasta	Fasta posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	Basically you have a "stick up" where the gelcoat has bonded to the paintwork of your original. Firstly 2 coats of wax is no where near enough, and then you should also consider using PVA too. You also need to be certain that your original/pattern paintwork is compatible and must be fully cured. When ever I mould anything (moulds and parts) I always use a semi-permanent release system like frekote (sealer and release coat) and then also 5 or more coats of wax on top of that. Read this- http://www.rexco-usa.com/why-molds-stick/ Fastacraft Facebook page Edited 10 Years Ago by Fasta
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Hanaldo	Hanaldo posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Totally agree with Fasta. 2 coats of release wax is never enough, if you're using wax alone then I would be doing 10 coats minimum. That said, I never use wax alone. Far too risky, as you have discovered. Like Fasta, I use Frekote semi-permanent release agent. If I'm doing anything that needs a gelcoat (like making a mould) then I apply 2 coats of wax over the top of the Frekote, though if I don't need a gelcoat then the Frekote itself is enough. To be honest though, I think for people without a lot of experience, semi-permanent release agents can be a bit tricky for making moulds. They are excellent and give the best results, but they can be risky in themselves because you need to be meticulous with your application and then they do make it more likely for problems like gelcoat separation and pre-release. Not to mention you need to be 100% sure that the surface of the substrate you are moulding is compatible with both the release agent and the tooling gelcoat. The most reliable release system in my opinion is PVA. It will never give you a perfect surface so you will always need to do some refinishing work, but if you spray it on then you will be close and you can be absolutely sure of a release.
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Dravis	Dravis posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 592, Visits: 1.9K	Definitely not enough coats of wax, or other release, and most likely combined with too long a cure time for the tooling gel coat layer when making the mould. I'm just assuming you used EC materials, as these are what I have most experience in using You really have to keep a very sharp eye on the curing state of the "green stuff" EC tooling gelcoat, in order to make the following layers bond with it. On the Part itself, If you used GC50 from EC for the "clear Gelcoat" either too short a cure time for the GC50 or way too long time... If left to cure for less than 2 - 3 hours at 20 deg, it will not bond properly to the epoxy laminating or infusion resin, combine that with not enough release treatment = delamination at the gelcoat(GC50) / CF "boundary" Been there done that ... If left for significantly longer than 24 hours at 20 deg. C again, the epoxy no longer bonds to the GC50 --- same problem as above .. (Not tried that particular problem yet ... ) This also goes for using pure Epoxy clear gelcoat... this has to be hit "spot on" for the "tacky" cure state, in order for the subsequent layers to bond properly to it. Too early and you get the fabric printing through, too late and you get delamination... "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 :-) Edited 10 Years Ago by Dravis
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Blackrat	Blackrat posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 20, Visits: 85	remember .. wax provides the slip and PVA provides a barrier .... once the mold has been seasoned and all the millions of tiny pores have been blocked up, then you can switch to wax only yes , there are guys who do wax only .... all i can say is well done and your braver than me ;-)
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alex.mc	alex.mc posted 10 Years Ago HOT Post Details
Group: Forum Members Posts: 18, Visits: 52	I use wax only, and yes it can be tricky! Wax only is not dissimilar to semi-permament in that you need to be fastidious in it's proper application. A bumper or splitter on a car with mixed materials is a difficult subject. The rubber may have absorbed any number of chemical deposits that the wax is incompatible with. thorough cleaning first with panel wipe(petroleum distillate) would help. As others mention, 2 coats is not enough. A minimum of 5 on an "easy" mould, and 10 on a difficult mould would be appropriate. My seasoned moulds however only require 1 coat between pulls now, I use wax only to get a high quality of surface finish from the mould. PVA is your friend! Applied correctly it WILL work! Solvent based are easiest, water based will give a better finish but be more sensitive to runs and dirt inclusion.
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