my fibreglass disaster......

[Ribenapigeon]

As a bit of practice prior to haveing a go at making some carbon fibre panals I had a go with some fibreglass. I made a nice plaster mould of a kickplate and prepared it with PVA and polished wax. I then had a go building up some fibreglass. Well, what a disaster. The fibre matting kept sticking to the brush I was using and then would start to break up. Then the epoxy went hard in about 3 minutes! When the tin said 20 minutes to cure. So made up some more and tried putting in anothe layer of fibre only for it to break up again and not able to push it well into all the corners as it kept sticking to my brush. I kind of expected this first test piece to go wrong so I'm not too bothered but some advice on how to do better next time would be appreciated.

Cheers.

[virus]

less hardener and ensure its mixed consistently.


Cheers
John
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own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.

[herulach]

My guess is you're using chopped strand matting, which does that. If you want it smooth you want woven roving.
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YBR 125>FZS600

[Snodvan]

Do not try to BRUSH-ON the resin mix. Use a STIPPLE action. Chopped strand matting will always come apart of you try a brush stroke action.

Snod
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04 (UK Reg) BMW F650cs, but really 02 first Reg in Holland

[Ribenapigeon]

Its very difficult to meaure hardener amounts. The pack advised 2 to 3 centimeters of hardener to 10mils of resin. I measured it out in 1c bits on a stirrer. Next time I will try being leaner on my measures.


Even with stippling it broke up I think the matting I got was too fine for the job.

[virus]

I normally pour the resin on then stipple it in, that way the brush doesnt seem to stick so much, dont worry about it looking cack on the first layer, you can always do another few resin coats to get an even finish.


Cheers
John
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own: 81 xs1100g...
owned: 85 rat CG (sold), 91 GS500e (stolen), 84 gsx400f (scrapped), 81 z250 (siezed, siezed, scrapped), 83 cb250rs (sold), 84 gpz750r ratfighter (killed) 84gpz400 (sold), '80 cb650 ratfighter (wrote off) 95gsx6/12f ratfighter (killed) 91 xj900 (sold)
stinkwheel Well I just had my hands up a pigs fanny. Which makes your concerns pale into insignificance.

[kramdra]

I havent used fiberglass much but best results with fibreglass tissue and epoxy.

I realise epoxy is fail, but ok for small things.


Thinking about using heat gun and a scrap ABS panel instead of resin.

[Ribenapigeon]

I first painted the mould with resin then rollered resin into the first layer of fibre, which seemed fine until stippling it into all the corners, then the resin cured in the pot. So then made another batch of resin with less hardener but sucessive layers of fibre just very difficult to handle I put a couple more into the mold dry (IE not rollered with resin). Popped out of the mould well though an hour later and with a good surface, so next attempt should be better. I wondered if vacuum bagging might have been a way to get pressure into all the moulds corner as well, or a heavy bag of sand.

[Nope.]

Getting the right Resin/Hardener mixture is quite an art, if your not 100% sure then I tend to use less and then dry it with a hot hair dryer which greatly accelerates the drying process. Also make sure you mix the hardener into the resin well and if you can't apply a cup full of resin at a time then use less and mix up a new batch more often.

With regards to the fibreglass matting, the matting that comes in those fibreglass kits tends to be absolute crap. If your only doing a small job then you can buy reasonably good matting from halfords (although it'll cost you!) you can get larger amounts at a cheaper price on ebay if you only want a few meters and are willing to wait. You might also want to try fibreglass tissue as the outer layer as it creates an easier bonding surface to press into curves and bends. It will pull apart as your trying to use it if you try to brush the resin on so you need to use a dabbing motion to apply it successfully. After you've got the first layer down you can start applying the thicker matting until your happy with the thickness, then make sure the matting is sufficiently impregnated with resin so you don't get any soft pockets and then you can leave it to dry. As I said above if you want it to dry faster you can apply soft heat with a hair dryer, I have a couple of tesco value ones (£3 each) that I use and it accelerates the drying process considerably.
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Former: Derbi GP1 50, Sachs XTC 125, Suzuki GSXR 400 GK73A, Kawasaki ZX7R, Suzuki DR250, Yamaha RD350
Current: 2011 Yamaha XT660Z Ténéré, 2003 Yamaha YZR-R1 5PW (In Build), 2009 Kawasaki ZZR1400

[Ribenapigeon]

It was some fibreglass tissue from Halfords I was using. i'll pop to Halfords tommorow and get some of the more robust matting.

[Nope.]

[Ribenapigeon]

Yup I thought the tissue would give a better surface. My bad.

[ruck bodgers2]

my experience was pouring it and then applying the matt was better like virus said in his post. it soaks it up better and you can just trim any overlay off afterwards . after u lay one matt down u can stick another in place over it. as its soaked through . can take a while to soak through properly . i made a seat pan that way its rock solid .
stuck my fingers together as well
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throw it up the wall

[i.p.phrealy]

I used to make fibreglass sheeting for factory roofs. if you need to clean anything afterwards use cheap nail polish remover, unless you have somewhere nearby that sells acetone (the active ingredient in nail polish remover).
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it is impossible to lick your own elbow...
and if you just tried you need professional help.
Finally allowed a big bike 19/03/14!