Who here has worked with fiberglass a little?

[Big Rich]

I might have more questions as I get more involved in a project, but here is one I've been having a tough time researching.....

What kind of gelcoat should I get for a "finished" fiberglass seat and how should it be applied? Looking around on Google tends to lead in 10 different directions..... I'm thinking just get some white gelcoat (and hardener I'm assuming) and brush it on. Wait for it to cure and then sand it smooth.... is there a better way? Any recommendations for particular products / where to buy?

[J_Walker]

I order/buy from here for building kayaks and doing boat repairs. their stuff is always fresh and doesn't sit on the shelves like some other places that will sell you 4+ year old resin and hardener. when you shouldn't use fiberglass/epoxy stuff that's older then two years realistically.

I don't work for them, nor get paid endorsements from them. I just order from them and have good experiences.

plus you can order cloth and resins from one supplier. and everything in between.


http://www.fiberglasssite.com/

[Big Rich]

Yikes! $60 + shipping for a gallon? I was hoping to spend a little less (and I don't think I'd be using an entire gallon).

Thanks for the link though Watcher. I'll keep it in mind.

[ShowBizWolf]

I wish I could help ya Rich but all the fiberglass work I've been doing so far is patching and fixing holes... I haven't gotten to where I need to do nice finishing work yet.

I use duraglas a lot to fill in gaps and smooth a surface... but it is on the more expensive side too. However..! ya don't have to get a gallon of it, they sell smaller containers.

[Joolstacho]

I've used a lot of 'glass (have the emphysema to prove it!!! )
I'd go Epoxy resin for sure, not Polyester. West Systems is good. Try a boat repair / marine equipment supply place (we used to call 'em Ships Chandlers).
You can make a gelcoat using laminating resin with added colour pigment (which is like a thick coloured syrup that you mix in with the resin).

Epoxy is: Easier to mix accurately, easier to control gel-time, stronger etc than polyester resins. Epoxy is more expensive, but for smaller jobs it's cheap enough.
500ml will do a seat unit easily with plenty to spare, prob cost you 20 bucks.

But... if you're not building a female mould, forget the gelcoat, it'll be a waste of time. If you're laying up over a male 'buck' (say if you're laying up over a fairing to get a copy of it) you're going to need to be using auto body filler to get a smooth surface.

If you need more advice, more detail on what you're doing would help.

[peteGS]

I'm no expert Rich and I've really only done the one decent bit of fibreglassing which was the tail piece on the 450.

I took some advise from Dale over on the GSR and patched any dents or recesses with some fibreglass matting cut up and mixed with resin like a paste.

Then I started layering on fibreglass reinforced body filler and sanding each layer back smooth until I was happy with the surface.

Then if there are any tiny imperfections or whatever you can use some putty or similar to touch up the little areas, again sanding back to smooth.

After that it was 2K primer and paint just like the rest of the bike.

[Big Rich]

Showbiz: All good! You still have a hundred times more experience than me with it.

Jools: I'm making a glass seat for my GR650 from scratch (the thread for it is here on the Twins too). Already have the tape, foil, wax, and the first layer of cloth & mat down. Just trying to plan ahead for the rest of the seat project.

Pete: I'm going to have to thumb thru your thread on the GSR again. Should have checked it already - don't know why I didn't.

Thanks fellas!

[peteGS]

Actually Rich, try this thread:

http://www.thegsresources.com/_forum/showthread.php?182912-Painting-my-450/page7&highlight=painting+450

It's in my paint thread, not the rebuild thread... around page 6/7 is where I get into sanding the tail piece etc.

I did have to deal with removing a layer of putty I tried first which didn't turn out so well... putty is good for that last little touch up before primer, not good as the first thing on the bare fibreglass... 

[Big Rich]

Cheers Pete! I flipped through about 75 pages of your build thread and couldn't find the good details.....and there's why! Haha....

[peteGS]

Haha yep! Sorry... just had to mix it up a bit... get it? Fibreglass and resin? Mix it up a bit? Well... yeah it was lame...

[Big Rich]

Well, I put down a couple more sheets of glass cloth today..... and my inexperience is showing. I tried using larger sheets of cloth and it flexed out while curing - leaving lumpy bubbles all over. I think if I tried filling in all the lower spots with filler and sanding it down, I will end up with a 50 pound seat. So I might end up using the current project as a mold anyway.

Boo.

Edit: unless I can sand down those lumpy bubbles and use the "chopped glass / resin mix" to help smooth everything out. Any thoughts? Or are pictures necessary?

[peteGS]

While the area I did was quite a bit smaller and I had no real large areas to lay it down on, I do recall having to really sort of push the resin into the mat as I lay it down. Of course that was after getting the mat nice and wet before putting it on in the first place.

I didn't have any issues with it bubbling up while curing doing that.

Pic's might help a bit but I would definitely have a go at sanding it back and seeing how it looks first. How many layers do you have on there now?

[Joolstacho]

You do need a bit of 'technique' to lay up around tighter compound curves. When doing this, you can make cuts with scissors before you wet the glasscloth out, -lay your cloth over the 'buck' (the 'male' part that you're moulding over) dry, then you can see where you need to make simple cuts where the cloth is 'folding' up from the surface, then you can smooth down, overlapping as you go. (In tailoring/dressmaking this is similar to the 'darts' they cut to enable flat cloth to shape around 3D surfaces... useless information!) There's no problem covering a surface using separate cloth shapes that will conform more easily to the 3D form, you just need overlaps. These techniques are much better than trying to cover tight compound curves and getting air bubbles in the job because the cloth won't 'conform'.

Using thinner cloth helps, or try chopped strand matt, (CSM) but when you use matt, get thinner matt, and the trick is to thoroughly 'scrumple up' the matt in your hands before using it, - screw it up, rub at it so it's all loose and fluffy, then lay it out and smooth it down over your buck dry, this loosens the fibres and facilitates them moving to conform to the 3D form as you go around compound curves.

You can also 'divide' CSM, - peel it apart to get half thickness. Thinner matt will 'do' compound curves easier. Most people use too much resin when 'glassing'. Don't do 'hot-mixes', mix ratios to allow plenty of time to lay up the job so you're not rushing. But I don't recommend trying to adjust gel-times by altering mix ratios as you will compromise strength and curing.

The cloth or matt will soak up the resin even when brushed on pretty sparingly. (You might be surprised how little resin you actually need, most of the work I did was moulding RC Jet Turbine and slope-soarer fuselages, where lightness was absolutely necessary, but without compromising strength, so we used absolute minimum resin, because the real strength is in the cloth/matt).

Like most things it does take practise. (Sorry it's a bit long-winded, but a bloke could go on about it for hours!)

[ShowBizWolf]

Thank you for sharing this Jools... I soaked up this info and will certainly put it to use!

[Big Rich]

Thank you for sharing this Jools... I soaked up this info and will certainly put it to use!

+1!! It may sound long winded to you, but it certainly didn't fall on deaf ears.

I'm in the garage tonight busy with a couple of projects, so it will be a quick reply. Pete, I basically have 2 layers down right now. The first is glass cloth in the seat area w/ mat down the sides and forming the hump. The second layer is all cloth and has the lumpy bubbles in it. And the second layer was the larger sections of glass cloth, which makes me want to point the finger at the larger sections causing the ripples / bubbles.

On a good note: I popped off the glass with some air pressure so I can see what needs trimmed down before continuing on....no point of pouring work into a section that has no chance of being in the finish part, right?

Thanks again to all yinz.

[Joolstacho]

Dead right Rich, just sand down through those 'bubbles' then patch them with glass, then when it's all gone off you can sand it, then use 2-pack auto body filler to fill the worst
sections, then use 2K hi-build primer to smooth everything off ready for your topcoat colour.

BTW what mould 'release' did you use? There are several options, here's mine:
Once your male buck or female mould are perfectly smooth and sealed, (We would finish down to 2000grade wet and dry, then cutting compound, but most day today jobs don't require this level of finish), polish it with mould release wax. Go through the the process again a few times if your mould is to be used for multiple 'releases'. Then I spray with PVA Mould release. (you can't brush paint this PVA on over the wax because it'll just 'fisheye') When that's dry I spray with a rattle-can paint called 'Appliance White'. This gives a safe 3-stage release.  This has never failed me.

Well,  apart from once... 

Ok, we were making final detail-part mouldings for the jet inlets of a turbine aircraft fuselage. (Many mouldings are complex mutli-part mouldings, I think this one was at least a five-part mould). We weren't moulding a part from the mould, we were actually making the mould from the original buck. Everything had been carefully prepped as usual, but what we didn't realise was that the compressor airlines has been contaminated with some chemical that inhibited the release system. (We used compressed air to blow off any dust before applying the release system). Man, this was an absolute NIGHTMARE. The new mould part was stuck solidly to the main mould and buck, the release system had failed completely. I had to painstakingly file and sand away the new mould section that had stuck (instead of releasing), then re-finish the main mould. Took days.

It still makes me feel sick in the guts to think about it!

[Hyperion]

I believe the place I went to is called Plastics World. Has everything you need.

[Big Rich]

Cheers to all yinz for the help!

Jools, I just used about 4 coats of turtle wax on the aluminum foil for my seat. It worked pretty well for me....but I'm not doing NEAR the type of glassing you're doing. I was more worried after laying down the resin about the tail section locking down due to its shape (pictures below). I'll definitely keep your release procedure in mind though - the less fighting the better!

So as I posted earlier, I ended up popping the fiberglass seat off with some air pressure and elbow grease. For those that didn't see it in the other thread, here's what I started with:

[Big Rich]

Popped off, and all the plastic / tape / foil removed from the bike:



Started trimming the edges a little (this is also where I'm at right now):

[Big Rich]

And to give an idea of how lumpy the fiberglass is at the moment:





I'm going to be sanding down the high spots on the outside my next couple of days off. Should I add some layers of cloth on the underside for structural support before sanding the top side down?

Thanks again for everybody's help. It is much appreciated.