Topic: First time fiberglassing - using bondo jelly

[narcoticrex]

Hello all, I am about to fiberglass for the first time and make myself a nice cafe seat.  I have already made my form, taped it with masking and then aluminum tape, and am about to hit the actual glassing stage.

does anyone have any tips?  How many layers? Im using fiberglass cloth and Bondo jelly.  Anyone used the bondo jelly before? Is it as strong as the resin kind? im under the assumption it is the same stuff, just in a different form that is a bit more forgiving.  I just dont want to end with a seat that isnt strong enough, or on the other hand end up with one that is 6 inches thick and wont fit on my seat pan anymore heh. 

how much of this stuff does it take to cover the seat once? should I buy another can before I start?

Thanks for any input.

[hymodyne]

I put two layers of fiberglass mat over a foam form, then put a layer of bondo over that. I finished with a layer of fine weave fiberglass cloth. I'm using my original metal seat pan, and left the foam in place. the seat pod in my avatar was the result after priming and painting.

hym

[merc2dogs]

 It depends a lot on how much curve there is in the part you're making.
 
 Curves add stiffness, so with the seat pod in Hymodyne's avatar a couple layers would be about perfect. If you plan on something with less curvature, use more layers.

 Fiberglass takes a while to fully cure and you can add on to it afterwards so if it's not as stiff as you like you can stiffen it up with another layer or two. Adding to it gives you a simple mechanical bond which is not as strong as the lay-up bond which is chemical but typically no problem on seats.

 Regarding the gell stuff, it sounds as though it may be too thick to properly penetrate the cloth, the strength and stiffness of the finished fiberglass is entirely dependant on how well the cloth is 'soaked' with resin. Dry spots are weak spots, properly laid up fiberglass is transparent so if you see white it's not laid up right.

Ken.

[gregk]

If you put two layers of woven cloth it will be strong enough on the "hump end" of the seat but you may find that the part where you ass rests is not strong enough.  Make some ribs out of 1/2" poly rope and glass them.  These will go across the seat area and strengthen the whole piece.  I used electricians snap ties to fasten the rope to the seat.  Drilled small holes through the base then you can lay the cloth over them without the rope moving.
Worked for me.  The ribs will go on the underside of the seat pan.

Good luck

[Soos]

Awesome tips, don't forget to do a search as this subject has been discussed quite a bit.

l8r

[silentone]

Here are a few links that may help:

http://www.explorerforum.com/fiberglass/fiberglassing.htm

http://www.fiberglassforums.com/

[troppo]

G`day mate
I havent heard of "bondo jelly" but just from the name i dont think it will work..
As ken said the strength is from the resin impregnating the cloth and i think a jelly would be far too thick.
I`ve been playing with the glass lately, and do a bit at work and you need to get a good clear look to make a strong panel, strength will vary on how many layers you use, the shape of the part,the weight of the cloth and whether its chopped strand mat or woven (woven is stronger than CSM but also more expensive and less forgiving with shapes).
As its your first time playing with fibreglass i would suggest you get enough matting and resin to make a couple of seats in case you stuff the first one(which wouldnt be unusual).
Its a smelly, messy and damned itchy process but at the end of it you will have that "i made that" feeling that makes the whole thing worth while
Cheers
Troppo