Outer Limits 4x4 Board

A question for the panel beaters,fibreglass experts.
I need to do some repairs and modify a fibreglass vehicle roof.The roof is at least 15 years old.
How successfull will the new fibreglass be on the old with regards to it sealing and not cracking?
Thanks
Gavin

I wouldn't say I'm an expert but I've done a few fibreglass jobs.
Boats, surfboards and pool repairs.


As long as you remove all gelcoat the new glass will stick to the old stuff no worries.
A good blow off with air and a wipedown with acetone will ensure the surface is clean.
Be sure to wet up the old stuff before laying dry glass on and then soak it with resin and roll the bubbles out.
To stop it cracking you'll need to lay glass inside and outside.
Do the inside repair and let it dry and then sand the outside down enough so you hit the inside repair and then repair the outside.
Jas.

First things first. Safety!

wear gloves. mekp (hardner) ios nasty shite. it is absorbed through the skin and your body will store it - it never leaves. every time your exposed you add to it. too much and ...

next face masks body protection. when sanding back any glass product wear a good breathing mask - this shit is like asbestos in some ways - not good for lungs.

when you sand it back you will get itchy as hell - its from tiny little glass shards sticking into your skin (like it would in your lungs) wear long sleeves - 2 layers is much better.

ok, assuming its not epoxy due to its age.

Is the roof smooth or corrugated?

smooth will be much easier to repair.

if currugated then use a much lighter weight glass matting, it will bend easier.

I tend to prefer to use multiple layers of woven glass rater than less layers of the heavier chopped strand. woven will bend much easier.

You dont have to remove all the gel coat, but the surface must be sound, not flaky, or dirty or soft etc etc. sometimes this does mean all the gel coat has to go.

basic rule of thumb is get everything ready then mix a small amount of resin. the amounts can get bigger as you get better at your work and can work faster - mix the resin and mekp accurately it will give you a longer working time.

wet out the surface to be glassed over (maybe 1/5 of the roof) brushes work ok, foam offcuts are my preference. then lay glass down smooth out wearing gloves. add a bit more resin (not too much) and work it into the glass, it will go more transparent when ite 'wet out'. use a roller or brush or foam to even out the resin, avoid peaks and dribbles etc as you will have to sand them of later. the do the next bit.

If doing multiple layers on each spot, do them all at once, dont let it dry between layers - it will bond much better.

if its corrugated then sanding will be a nightmare, if not grab the orbital and go for it once its fully dry.

using a product like peel ply might be worth while, but with a curving roof it can be difficult, it is like a final layer you put down to smooth everything out a bit, then when its ry you peel it off and it gives a smoother finish - textured though.

the inside will be hard to do unless you can remove it and turn it upside down. doing glass work upside down is very hard and messy.

you will not need to do both sides unless it is badly cracked or you plan to walk on it etc. if you plan to walk on it,then we need to look at bracing etc.

pm me if you want any specific help or need photos etc. im happy to help.