Filling Holes In Fibreglass

[Guest mcramsay]

Post IVA & im looking for small jobs to keep me busy over the holiday period. I have some 5 &6mm holes in the fibreglass body that need filling as I had to move my wing mirrors for IVA. What's the best method for filling, isopon fibreglass fillter rubbed back with stopper filler on top or just normal bodywork filler and then stopper?

[Bob Tucker]

I'd suggest putting a patch of mat & resin behind the hole to reinforce it,

then fill from the front with regular filler applied in several thin layers once it is dry.

[Guest mcramsay]

I have some spare matting & resin so that should work

[femster87]

Rough up the surface to provide better key

[Guest mcramsay]

Out of interest what grade of paper should I rub back with? I have done bodywork on metal surfaces. Before but with fibreglass I have this image of rubbing the filler back and ending up putting a large dent in the surrounding material!!

[Guest Tim Norman]

I have in the past taken a blow torch to the area to burn a way the resin to leave the glass strands visible. gives a better surface to bond to.

[Bob Tucker]

Tim's method will work, but GRP is flammable.......be careful!

 

Mat & resin provide a mechanical and chemical bond.

I'd use a wire brush &/or coarse sandpaper to roughen up the rough (back)

side of the GRP, then clean it up preferably with acetone (nail polish remover)

or cellulose thinners before laying up the mat.

 

To rub back the visible (outside) surface, use wet & dry paper,

start with 180 then go on to 320, then finish with 600 or 800.

Use it WET & rub a bar of soap on the paper before attacking the GRP.

To avoid any dips, always use a block to support the wet/dry paper.

A rubber car finishers block is best, but a cork decorators block is just as good.

You can also use a piece of blue or pink insulation, anything with a bit of give.

Not a block of normal wood.

 

Theres lots of info on the net..

https://www.google.co.uk/search?q=how+to+repair+a+crack+in+fibreglass&rlz=1C1CHFX_enGB536GB536&oq=how+to+repair+a+crack+in+fibreglass&aqs=chrome..69i57.9802j0j7&sourceid=chrome&ie=UTF-8#q=how+to+repair+a+hole+in+fibreglass