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Pertabolis
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Hi I was wondering if it was possible to dissolve the PU 80 low density model board in some solvents after having laminated a CF cloth around it ? The idea would be to - cut the foam to the target shape - apply the epoxy/CF cloth - dip the hole thing in a jar of acetone / other solvent
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baja_patient
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[COMMENT BY EASY COMPOSITES TECHNICAL SUPPORT STAFF: ANSWER INNACURATE; SEE OUR POST BELOW]Yes, acetone would disolve the PU board no problem. However, the problem you will have is that the part will most likely be destroyed as the resin will most likely disolve too, at least it will be attacked. what are you trying to make? I'm sure someone else will chime in on this. cheers
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Pertabolis
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Group: Forum Members
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Are you sure you can dissolve an epoxy like that ? I am trying to design a case for my phone (small project) and I thought an easy way to have the right shape would be using the PU foam cut to size, and dissolve it after the epoxy is cured. The other way that I thought is to make a wooden model of the phone (e.g. balsa wood) and wrap it on a PP sheet. Once the epoxy is fully set, I can pull the wood out, then peel the PP sheet off (and no release agent required). Thanks for your answer Baja_Patient !!! P.
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baja_patient
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I'm not sure if it will dissolve fully cured epoxy, but I still wouldnt bet on it. You are on the right lines with the wooden core, but I would model your part in wood, or machine it from aluminium or dense tooling material. Then I would make a female mould from it. For a phone case I would just make a top and bottom half and then join the two sections. nop probs. I hope that helped. cheers
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Pertabolis
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Group: Forum Members
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Thanks very much indeed ! My idea of a case was more something like that http://www.technologytell.com/apple/57482/iphone-4-cases-2/ (the first picture on the webpage). Something I could slide the phone in and out. Then I need to wrap the CF around a male model of my phone. A dense wood would definitely be better but the balsa helps me to obtain the right thickness as I will cover the inside of the case with some soft fabric to protect the phone. My issues are with the right angles where I have less fiber and this is really easy to damage. But I'll work it out !
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baja_patient
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Group: Forum Members
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Good stuff! Yeah I get what you are trying to do. Should be relatively straight forward with a design similar to the one in the picture. But dont forget, CF is a radio frequency blocker. You will lose considerable signal with a full carbon case. Perhaps try black diolen.
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Matt (Staff)
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Hi Pertabolis,
Actually acetone won't dissolve polyurethane foam or model board. Polyestyrene foam (like Styrofoam or bead-board insulation) is the type of foam that would be dissolved by a strong solvent such as acteone, PU would not really be affected at all.
Regarding the epoxy, that would not be affected by acetone, certainly not over the lengths of time it would take to dissolve away an internal foam core so the process you're describing would be absolutely fine, providing that you use a polystyrene foam core and not a polyurethane one.
Best regards, Matt
Matt Statham
Easy Composites / Carbon Mods - Technical Sales
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baja_patient
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Hi, I'd like to apologize for the false information. I got my foams mixed up. I built a surfboard once and regular styrofoam and high density closed pore foam were non compatible with polyester. As for the acetone, I poured it into a regular plastic drinking cup, the cheap throw-away kind which I assume is PVC, and the bottom just fell out instantly. I was using class A acetone, which I bought from an epoxy supplier specially to clean epoxy tools. As for dissolving the cured epoxy, I had a strong hunch that its chemical proof-to resistant when fully cured. It did however come to mind that in your uni-mould video, the first one, you use acetone in a spray bottle to tack the cloth to the cured resin. Then I remembered it was polyester. Anyways I am obviously by no means an expert and am learning everything I can. I now know more and will thus shut up for a while!  Good luck with the project. Cheers
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Pertabolis
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Group: Forum Members
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No worries the forum is there for that  and Thanks Matt for your help.
Baja I thought at using diolen but it seems quite difficult to sand/polish and obtain a nice finish. My process needs that I sand the fiber then polish, and I quite like this effect (in opposition to a real glossy surface). |
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Matt (Staff)
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Group: Forum Members
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Hi Baja,
No need to apologise; I guessed as much and that is what the forum is here for after all.
Pierre, regarding your material choice, diolen will be problematic if your surface sanding will break down into the diolen. If it won't and it's just the edges then I think that, allthough a little more frustrating at the edges, you woud be able to work with it. If you think you'll sand down into the diolen on the surface then stay well clear, it would be very hard to deal with in this sense.
Best regards, Matt
Matt Statham
Easy Composites / Carbon Mods - Technical Sales
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