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Hanaldo
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Group: Forum Members
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Hey all, I have an issue that I have never experienced or heard of before so I was hoping someone might be able to help me. I have just finished making my tea trays with flax, jute and carbon fibre, infused with epoxy resin. Using Frekote 700 release agent. When I removed the parts from the mould, they were perfect. Shiny and smooth, exactly as I wanted them. Then a few days after demoulding, I trimmed the first tray up. After washing the dust off with soap and water, a sticky cloudiness began to appear in patches. Starting along the edges, it almost seems to spread over the part. Nothing I have tried can get it off, I've tried acetone, soap and warm water, I even sanded it back and then polished it up again, but it just doesn't come off. Strange thing is I can sort of smudge it around with my finger, and it even balls up as if it were a wax or something, but can't remove it. For the few days while I was doing this, the other part remained perfectly shiny and smooth. I could wipe a paper towel over it without it feeling tacky anywhere, so I happy. Then I trimmed it up, and voila, sticky cloudiness. It's only after trimming the part that it develops? Any thoughts?
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Hanaldo
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Group: Forum Members
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In case pictures help, this is straight out of the mould:  This is first tray (on the right) trimmed and cloudy vs the second tray (left) untrimmed but still perfect days later:  And this is the second tray after trimming: |
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brainfart
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Probably not an explanation for your problem, but have you considered water wicking into the fibers on the exposed ends?
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Hanaldo
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Yes I had considered that, but given this residue is on the surface of the epoxy and not underneath, I considered it unlikely. Is it possibly amine blush? I am using an epoxy that I haven't tried before, and have never experienced blush with my other resin system. That would explain why the acetone doesn't remove it, but I though amine blush was water soluble and should have washed off?
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brainfart
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Group: Forum Members
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Amine blush is caused by water vapour and CO2, so it is unlikely to appear in an infusion. It's also weird that it appeared days after it had cured, amine blush should appear during curing, so I assume it's something else.
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Matthieu Libeert
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weird stuff! can not find any possible cause and never read or seen about it before...
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benet
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i have found that particularly IN resin will take a long time to cure and will absorb water and become cloudy if worked before it is fully cured. My experience involved wet sanding a part that had been made with IN resin and fished with coating resin. When i wet sanded the coating resin everything was fine unless i sanded through to the IN resin underneath and then bad things started to happen in much the same way as you are describing. Cloudyness - patches moving around, spreading and no hope of improvement. the more you work it the worse it gets. I would try either baking before you do any finishing. Or . dry sanding then vacum and lacquer with 2k all wearing gloves to prevent any contamination on the surface. I do something like the later but i finish with coating resin not 2k as i need a very durable finish. Basically its the water in my opinion.
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Hanaldo
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Hmm it's possible as this is the first time I have used an infusion specific resin... However I washed both trays when I removed them from the mould, and that didn't cause any issues? It was only after trimming that the problems started...
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Warren (Staff)
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Flax is very hydroscopic so wicking could be an issue. The surface of the resin would be hard but wicking might be enough to take moisture deep in.
I'd try baking it off and see if it drives out the moisture as it postcures.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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Hanaldo
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Group: Forum Members
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Hmmm, thanks Warren. I'll try baking it. It definitely seems more like a residue on top of the resin though, it's almost like greasy finger-prints that just won't come off. I should have thought about the open fibres more, I was aware they are hydroscopic. Lucky this project is a bit of fun and not a customers order, I actually don't mind learning hard lessons when it only affects me.
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