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I don't normally photograph an entire project, but seeing as I had some free sample prepregs from 2 different suppliers I thought I'd turn it into a giggle. They both know I use VTF, and they assured me that their materials would compete. They told me that although the materials are made for autoclave, that I should see promising results OOA. I didnt get my hopes up as Ive tried several before and they all sucked.
I thought I'd turn it into a simple little project to play with these samples. The idea was to take a wooden part (as wood is something I haven't replicated before) that had a simple shape (I didn't have much hope for snything that isnt VTF). Nothing that would take longer than a week. So here it is, from original part to polished carbon copy:
Original wood part:
I tryed using teak oil to seal it, but that didnt work, it just kept sucking the oil, grain was still open.
So I used aluminium tape:
Flanges:
I knew I was gonna have to sand the stripes left by the aluminium tape, so i took the safest route which was to take a mould off the B side, this would in turn become a plug which I could sand down, most likely sanding the gelcoat quite thin. If I sand too far into the gelcoat, I dont have to worry as I will be taking a proper mould off it later. So making of the plug, followed by the mould:
Sanded the lines down with a block, and tried to get rid of negatives on the flanges. You can see why I did it this way, the grey spot there is where I sanded through the gelcoat into the skin coat, theres other spots like it and you can start to see the grey show through the green:
Postcure:
Taking the ali off was a right bitch, and it left a residue which was even harder to take off. Next time, Ill find a better way to do this:
To the prepreg room! Sealed and released:
Thawing and cutting the material:
Layup:
Bagging:
Bake:
Fresh out the oven:
Releasing was this easy:
Oh dear, it seems there was a bit of bridging. Im not surprised. As Iv'e said before, nothing beats VTF. These two photos were sent straight to the sales rep. Hes sending another sample  :
No carbon is scarp though, so I battled on. My plan was to fill the voids, mask them and put black stripes at the ends:
Sanding:
Some peeps on here get paranoid about fillinf the pinholes and voids with dust. Its nothing to worry about, the dust is transparent, and a layer of clear will make it dissapear:
Before the next coat, I'll try something new, branding. I've got a vinyl cutter, plus I made all of my branding myself, so I have the vector files, seemed rude not to do it:
The masking didnt really work, but I think it looks quite cool, even if by accident:
So, more sanding and lacquering, until the pinholes were filled, now go up the grades 400, 600, 800, 1200, 1500, 3000 then compounds coarse then fine:
Finished product on my desk:
Determined not to be beat, I remembered the second sample I had. Along with some new found knowledge gained from this paper:
http://digitool.library.mcgill.ca/webclient/StreamGate?folder_id=0&dvs=1371902526959~725
You could read the whole thing, or I could summarize it to this:
DONT USE BREATHER!
As simple as it is, I did learn something. If youre making a part out of wood, don't use ali tape. Two reasons. First, You have to sand back the gelcoat to get the lines off, and hence making your mould weaker (unless you did the plug-mould method I did. And second, if the original is not sacrificial, youre going to have a hard time taking the ali and its adhesive off very carefully. WD40 got it off without staining it, but I wouldnt place a bet if it was a different wood that was untreated.
I will also be commencing production without breather on the part, just on the mould.
Overall good experience, and the tea tray sold for £150 (for a weeks work!). Hopefully you guys can take something from it too.
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fgayford (03/08/2013)
wozza (25/06/2013)
Any Marine grade Polyester will give good U.V protection.  Now that is news to me. I have never heard of polyester that was UV resistant. I know boat people use it as long as they cover it with paint to protect it from UV destruction.
Polyester gelcoat finishes turn to chalk if left in the sun without protection. Epoxy does as well. Unless I am missing something this doesn't right.
Also you shouldn't be using polyester resin with carbon fiber in the first place as the laminate will be much weaker than with epoxy which is what carbon calls for. I think some of the experts at EZ Composites need to chime in and clear this up before someone makes some costly mistakes.
Fred Actually wazza is right. Any marine grade polyester resin is likely to have a high level of UV stability, especially compared to epoxies, and anything lloyd registered is of a good quality standard full stop. Most clear polyester gelcoats aimed at our market are again UV stable. Its only the cheap rubbish that is unlikely to offer it. You get what you pay for. There is nothing wrong with using polyester resins with carbon fibre. It IS weaker compared to vinylesters and epoxies but it is cheap so has its place. You will find the vast majority of premade cosmetic carbon sheeting offered in the UK and europe and especially any chinese imports, are all polyester based. Also a lot of cheaper carbon panels on the market are polyester based. Sure they are not as strong as they could be with epoxies, but then they don't necessarily need to be as strong for thier intended market. Sure if you want to maximise the performance of your part with advanced composites such as carbons etc then using epoxy based (or at least a quality vinylester resin) resin will be high on your priority list. But all us carbon nutters have to accept that a large part of the "carbon fibre" market is based on its cosmetic appeal (especially in the car world) and many such people couldn't give a damn if thier carbon bonnet (well 1 skin carbon, rest e-glass) is 40% heavier than an epoxy equivilent.
Warren PenalverEasy Composites / Carbon Mods - Technical Support Assistant
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