Good finish with fiberglass
 

Looking to start a build very soon and wondered if any body can recommend any good books or web sites on getting a near perfect surface finish to a fiberglass body. My main aim is to end up with a surface finish as near to steel as is possible, any advice welcome.

Suggest you paint it (rather than rely on gelcoat). As with a steel bodied car, the quality of the surface (re lumps/bumps) has to be good or the finish won't be good once painted. I'd suggest if filling any areas of GRP prior to painting, then be very selective with the filler because most shrink back.

Thanks Mitchelkitman, My intentions was to paint the body but it was the prep work i am a little unsure of, can you recommend a suitable filler that does not shrink and is fine enough to fill any small pin holes/imperfections.
IS there a time limit to leave the filled shell before painting to make sure any shrinkage has occurred before painting.

I think it's best to use something from the specialist places - I'd recommend East Coast Fibreglass (I've no connection other than being a satisfied customer). I'm sure they can advise better than I.

Normal filler can be used ok as long as its flexible and the same rules apply to fibreglass as to metal bodies, filler is for small imperfections not filling holes or building up large depth profiles.
If you do have a large sunken area a couple of tips that might help
A. Get some heat on the sunken area and apply constant pressure from behind with a prop of some sort, quote often you can get the fibreglass to move. If you then keep it propped from behind whilst it cools it should stay in the new shape.
B. if you do need to raise the profile of a panel consider grinding the gel back and building it up with layers of fibreglass then finish with bridging filler and final finish with a flexible filler just to smooth the surface if required.

When painting fibreglass i always use and etch primer first, opinions differ on this point but it's always seen me alright. Normally just a single coat of etch then straight onto a couple of high build for wet flatting down before top coat.

Another tip is to get the body into a heated booth and get it warm, or you can use a heat gun with care. This will reveal any voids in the fibreglass as the air trapped in them will expand and show as a blister when heated, nothing for it but to dig them out unless you want your car to develop a lumpy body on the couple of days a year it gets warm enough :-)
HTH

Mac

I've heard about repairing sagged areas using the method you describe - but won't putting the car in a heated booth create similar problems?

No you need far more heat to get a panel to move than you do to get the air to expand and show the blisters, you would still be better though doing the blister check before you did anything else so and slight distortion can be tackled after the blisters have been removed.
HTH
Mac

Thanks Viatron, what temp does the booth run at to show up any air pockets.

Also you mention the use of etch primer first, is this the highly dangerous stuff where breathing apparatus is required.

Yes its dangerous but like anything as long as your sensible it can be used in a domestic garage with the right precautions, that said just straight 2 pack is just as dangerous as well.
Temperature wise the last time I used a mates booth to check some panels I just whacked it up to max for 30 minutes and that showed a small void. Next time I'm over I'll ask him what his booth tops out at.
Mac

Cellulose paint is the choice i will go for due to the fact of requiring air apparatus for 2 pack. Another point which is mentioned on a number of sites is to buy the most expensive spray gun you can afford so will start to do a bit of homework and see what is out there.

Just bear in mind that if your spraying at home in a domestic setting celly can be almost as bad for you! You could also go with a synthetic , sometimes called truck coat, it goes on quite thick but gives plenty of options for flatting back and polishing once it's fully cured.
With the heating to find blisters you can also use an infra red lamp and just move t around the car panel at a time, might be easier if doing it at home.
With spray gear I wouldn't get too fussy about the gun, don't buy the cheapest but definitely don't need to go top shelf either, you can spend a fortune on a gun but if you are still learning you won't see the benefit.
Don't rule out some of the newer HVLP kit either, not used one myself but know a couple of people who have tried them with good results.
HTH

Mac