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Wasn't sure if this should go here or in hobbies. I'm working on a kit car, 1962 Ferrari body on a 76 datsun frame. I picked it up super cheap with all the hardwork done. The kit was already mounted, frame reinforced, everything done pretty darn well. I'm a bit of a perfectionist, so I really want these seams to line up well. I've been doing a ton of fiberglass work laying and sanding to get everything to line up well but I'm looking for a few pointers. I'm not a total amateur when it comes to this stuff, but I am looking for tips on how to build out a fiberglass edge. The one spot where the hood lines up with the top part of the door frame is a gap about twice the size of all other door gaps so I need to build it out about 1/4 inch. I started laying cats hair fiberglass one layer at a time, sanding/shaping the correct curve then laying another layer folding around this edge. It seems to be working but is slow moving and I'm hoping is the best way to do this.
Also, when using glazing putty, I know its really meant for little pinholes, but what about slightly larger uneven spots or little divots. Whats the max size fill area? a dime? a quarter? and how deep?
Also, when working with these edges I have a bit of shaping/filling I need to do. I was thinking of using a glazing putty over the fiberglass, sanding to the shape I want, then basically painting over it with just the fiberglass resin to keep it all tight as I know body putty has a tendency to crack.
When all done I plan on using a plastidip paint as the whole body is fiberglass and is going to want to move and flex and I'm hoping the plastidip will have more give then your standard paint job and wont lead to those spider cracks every where.
Location: East of Seattle since 1992, 615' Elevation, Zone 8b - originally from SF Bay Area
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I have used body filler and glazing compound not only for auto body work but also for several years when I worked part-time repairing department store mannequins. The glazing compound is meant for the edges of the bondo, or slight scratches, not for anything deep. It may take several applications with sanding in between, but I would not go more than 1/16" total thickness, 1/32 is better. Deeper pits or scratches should be filled with fiberglass or epoxy.
[quote=ericp501;48487595]
Also, when using glazing putty, I know its really meant for little pinholes, but what about slightly larger uneven spots or little divots. Whats the max size fill area? a dime? a quarter? and how deep?[quote]
Don't use glazing putty for any of it. Use a flexible primer surfacer like K 200 to fill the pinholes and something like Rage Gold to do any divots that are too deep for the primer/filler to fill.
I use it on show cars and race cars to good effect, as well as fiberglass kit cars and blending fiberglass components on steel body cars.
Glazing putty is 1) not flexible enough for the fiberglass and 2) tends to bleed into the paint. it was a cheap band-aid back in the day, but it's really not the way to do it.
Quote:
Also, when working with these edges I have a bit of shaping/filling I need to do. I was thinking of using a glazing putty over the fiberglass, sanding to the shape I want, then basically painting over it with just the fiberglass resin to keep it all tight as I know body putty has a tendency to crack.
CHEAP body putty can crack, and glazing putty will not support itself at all. Use, again, something like the Rage Gold. It's fiberglass resin, lightweight and flexible as the fiberglass is.
Quote:
When all done I plan on using a plastidip paint as the whole body is fiberglass and is going to want to move and flex and I'm hoping the plastidip will have more give then your standard paint job and wont lead to those spider cracks every where.
The spider cracks are in the gelcoat on that sort of fiberglass, or in laquer type paints over fiberglass/plastic/ or even steel. If you use a good basecoat/clearcoat paint with flex additive in it, it will not crack or anything over fiberglass. I mean, think of what is used on modern flexible bumpers that is designed not to crack as they flex.
[quote=Tiffer E38;48489978][quote=ericp501;48487595]
Also, when using glazing putty, I know its really meant for little pinholes, but what about slightly larger uneven spots or little divots. Whats the max size fill area? a dime? a quarter? and how deep?
Quote:
Don't use glazing putty for any of it. Use a flexible primer surfacer like K 200 to fill the pinholes and something like Rage Gold to do any divots that are too deep for the primer/filler to fill.
I use it on show cars and race cars to good effect, as well as fiberglass kit cars and blending fiberglass components on steel body cars.
Glazing putty is 1) not flexible enough for the fiberglass and 2) tends to bleed into the paint. it was a cheap band-aid back in the day, but it's really not the way to do it.
CHEAP body putty can crack, and glazing putty will not support itself at all. Use, again, something like the Rage Gold. It's fiberglass resin, lightweight and flexible as the fiberglass is.
The spider cracks are in the gelcoat on that sort of fiberglass, or in laquer type paints over fiberglass/plastic/ or even steel. If you use a good basecoat/clearcoat paint with flex additive in it, it will not crack or anything over fiberglass. I mean, think of what is used on modern flexible bumpers that is designed not to crack as they flex.
Bondo makes a good polyester resin (not to be confused with the heavy rubbery reddish-white traditional "Bondo"): Bondo Fiberglass Resin, 401. This has some advantages over epoxy, but will NOT work on foam, as it dissolves the foam. It is good for build-up of multiple layers of fiberglass cloth atop of each other. It also works to in-fill minor cracks or divots.
To build a sharp (more or less) edge, I recommend taking a round hollow dowel of carbon-fiber, say 0.125" diameter. Slice it in segments, to go around a curve, such as the edge of the hood, where it meets the base of the windshield. Glue each segment of dowel to the rest of the hood, using 5-minute epoxy. Then wrap the fiberglass cloth over it, using the aforementioned Bondo polyester resin. Use something like 2-oz cloth, in multiple layers.
Also, for Datsun-based conversions of various kinds, visit forums.hybridz.org. Several members there have used the Velo Rossa kit for "Ferrari" GTO conversion from a S30 Z.
[quote=Tiffer E38;48489978][quote=ericp501;48487595]
Also, when using glazing putty, I know its really meant for little pinholes, but what about slightly larger uneven spots or little divots. Whats the max size fill area? a dime? a quarter? and how deep?
Quote:
Don't use glazing putty for any of it. Use a flexible primer surfacer like K 200 to fill the pinholes and something like Rage Gold to do any divots that are too deep for the primer/filler to fill.
I use it on show cars and race cars to good effect, as well as fiberglass kit cars and blending fiberglass components on steel body cars.
Glazing putty is 1) not flexible enough for the fiberglass and 2) tends to bleed into the paint. it was a cheap band-aid back in the day, but it's really not the way to do it.
CHEAP body putty can crack, and glazing putty will not support itself at all. Use, again, something like the Rage Gold. It's fiberglass resin, lightweight and flexible as the fiberglass is.
The spider cracks are in the gelcoat on that sort of fiberglass, or in laquer type paints over fiberglass/plastic/ or even steel. If you use a good basecoat/clearcoat paint with flex additive in it, it will not crack or anything over fiberglass. I mean, think of what is used on modern flexible bumpers that is designed not to crack as they flex.
Also, when using glazing putty, I know its really meant for little pinholes, but what about slightly larger uneven spots or little divots. Whats the max size fill area? a dime? a quarter? and how deep?
Thanks for all the great info!
tiiffer beat me to it with some excellent information. anything you use i fiberglass has to be strong yet flexible, including the paint/gelcoat. if you choose to use paint on fiberglass, you need to use a flex additive just like you would when painting the endura bumpers on 70s pontiacs.
I've done a bit of fiberglass work on boats and fiberglass bodied cars, so here are a few things to consider.
There are two kinds of fiberglass resin, polyester and epoxy. Polyester is probably what your car was build from originally, but epoxy is the better of the two for going back and doing any subsequent work. It bites in better and is much stronger, also more expensive.
I work with a product line made by West System. They have a very high quality epoxy resin, various hardeners ( some cure faster than others for use in various temperature climates) and a lot of fillers that you add to the resin to make it thicker for filling gaps and voids. It is not cheap, compared to polyester, but it is simply much better.
Get yourself a good book on either doing fiberglass car work or boat work.........both will feature tips on how to do various fiberglass repair work.
Resin, by itself, has very little strength, it is the cloth or mat that gives it the strength. I like to work with mat vs cloth. It conforms to shapes better and is easier to wet out. It also leaves less "print through" when cured.
To save money, buy your supplies at a marine supplier who deals in fiberglass products, not one of the places that sells mat and cloth in prepackaged amounts. It is cheaper that way.
Oh, and wear a full paper suit, vinyl gloves , and a dust mask when grinding or working with fiberglass. I have laid awake itching many nights because those little slivers get into your pores and you will itch like mad until they work themselves out.
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