Fibreglass tank painting prep

[searbs]

Hi, I am need advice on fibreglass fuel tank prep prior to painting. I have sealed the insides with KBS sealer, on the outside can I bog with filler, undercoat then paint, or do I need to seal with gel coat or similar prior to painting?
Thanks in advance
searbs

[flattracker]

You can bog straight to the gel coat. body filler and gel coat are both types of styrene so the bond is good, but you must sand the gelcoat to give the bog something to "key" to. 400 grit paper will do. then you can under coat and paint as normal. just try not to sand through the gel coat. You only need to deglaze the surface.
Happy painting..

[Lozza]

You could use the fibreglass with chopped strand or stainless strands in it already and use spot putty to fill the small voids. Fun begins after it hardens, a tip an old school panel beater told me is to run your fingers over the repair with your eyes closed, it helps you pick any undulations

[searbs]

Thanks for the advise, if the original gel coat is damaged do I need to reaply gel coat, I think I read somewhere that if I don't then the paint will crack. Anyone know if this is correct? Thanks

[flattracker]

No need to reapply gel coat. If there are cracks in the gel coat you need to use a Dremel or similar tool to dig the crack out of the gelcoat. Dont go beyond the gel coat though!! Then you can fill in the little "trench" with some resin, sand when cured, and continue with the filler, undercoat, paint process. Yes if you dont repair the gel coat cracks it will damage the final paint coat..

[searbs]

Thanks Flattracker, seems the gel coat seals the glass fibres, i will get on to the repairs to the Ossa Super Pioneer tank, cheers, John

[matcho mick]

gelcoat dosn't "seal" the glassfibres,it's the 1st thing to go in the mold???,it externally protects the layups,UV degradation etc,(& can be the colour),also protects the mold from fibre imprinting,(talking production molds here),would have thought after dremmeling the star crack,(typical impact failed gelcoat) reapplying a gelcoat would be preferred to just resins,(different expansion parameters  ),but then again gelcoat (to my way of thinking ) is just liquid bog, so do try & match it before painting,
ps Dulux Hy -fil ,an oldie but a goodie 

[searbs]

Thanks mm, further sanding of the repaint job has revealed the damage to to glass is from riders knees rubbing thru the gel coat into the resin and fibres. I think to best option would be to strip back to to coloured gel coat layer all over ( including where gel coat rubbed off), then roll a couple of gel coats over the entire tank, then use body filler to sort out any low spots. What do you reckon?
Also, if I want to colour the gel coat, what type of paint do I need to use?
thanks
Searbs

[matcho mick]

err,wouldn't bother re gelcoating allover,(tad tricky),just fill in the cracks you "dremel" out with gelcoat,& where you say riders knees damaged tank,as long as it's not structural damage,just cosmetic??,don't worry about it??,"kiss theory",cheers 

[searbs]

Thanks Matcho mick, I will use the less is better with the gel coat advise, only where required cheers, Searbs