Fairing the hull Questions for those Who Have Gone Before

[Maria CS20 104]

Once again, in my inadequate experiance, I have questions about the material for fairing the hull.  I have a buddy who has a five gallon bucket of "BONDO?"  He works on cars and he is willing to "give" me a 5 gallon bucket with kit he has not used, it is sealed and has never been opened.  He bought it about a year ago and he said it might be just what I need to fair the hull.  First, what is BONDO and is it compatible to the project for fairing the hull, will it bound to the plywood?  Should it be used on a boat?  What is it made of, he claims it is easy to shape, easier than thicked epoxy, but the epoxy he uses does not seem to be anything like what we are using, less hardner more juice.  Should I accept the "gift", Will it work?  I intend to coat the hull in 3 coats of the B&B epoxy after I do some fiberglass work on seams and forward hull and transom sections, so will it hurt to use this stuff?  Is it easier to sand and shape as he claims and is it compatible with the B&B epoxy?

Jim

[Ray Frechette Jr]

Bondo is Polyester resin mixed with talcum powder.

OK,  Probably has some other proprietary stuff too, but that is the lion's share.

polyester resin has high odor due to styrene.  So it will stink out your shop and if the shop is attached to your houdse,  cause problems with your wife.

Yes, Bondo is easier to shape and eaiser to sand and cures within an hr enough to sand and crecoat and it is cheap.

Bondo is not nearly as water resistant as epoxy and will absorb water and Bubble up afterwards.

Think Osmotic Blistering with a vengence...

OK,  Bondo also does not adhere to wood terribly well either.

You can apply epoxy on top of bondo, but bondo on top of epoxy is far more problematic.  Any unreacted amines on the surface of your epoxy will prevent bondo from curing at the immediate interface between the two products  The bondo will seem cured and hard, but a good solid rap will cause it to slide off the epoxy.

Now that deonst mean it will happen every time as you might have the magic batch of epoxy withthe exact perfect mix of resin to hardener that will not have unreacted amines left over..

Or you could do such a wonderfull jpob of washing, sanding and washing off again that maybe you might get a good cure and adhesion...

But I wouldn't trust it myself.

I would say thanks for the offer,  but I would'nt use it

[John Burritt]

I agree w/ Ray.  Fair epoxy w/ epoxy - thicken it w/ microballoons, Microlight, or other easy-sanding filler. 

[PAR]

Nope, don't use the stuff. Ray's pretty much covered it. Polyester doesn't stick well to epoxy, particularly in large thin layers. For a pin hole or two, sure, if you've got nothing else, but honestly it doesn't belongs on a boat.

I'll add fairing isn't a place for short cuts of any kind, they just show up when your fresh paint job sees direct sun light for the first time. Shop lights just don't show you the real surface like real overhead sunshine. If there's any questions, this is when they'll turn up.

[Tom Lathrop]

Ditto all the above advice.  Thank him but don't use the Bondo on a boat for all the reasons given.  Labor is always the largest investment in finishing off a boat and that goes double for fairing work.

[Steve Day]

The guys have the right idea. Bondo is NOT what you want to use on a boat.

Use epoxy thickened with micro-balloons, or some other comparable, easy to sand filler. You do not want to take shortcuts in this stage of construction.

Steve

[Dogdad]

The System Three Quikfair epoxy works well and is very easy to use, but is usually more expensive than mixing your own.  Time vs. money...

http://www.systemthree.com/p_st_quikfair.asp

[John Turpin]

The System Three Quikfair epoxy works well and is very easy to use

QuickFair is a wonderful product and great to use.  When I've used it, I've always been shocked with how quickly I run through those little tubs and how much I'm spending on it.  This time, I'll be fairing with microballoons.  Hopefully, it will cost me a little less and still provide those great results.

[Maria CS20 104]

Thank You Thank You one and All, had one of those itchy feelings and did not feel right but never used the stuff for anything and don't recall even hearing about it, pretty sheltered here in North Central Louisiana and I DO NOT DO CAR WORK .... EVER

Thanks Folks

Jim

[ChrisObee]

QuickFair is a wonderful product and great to use.  When I've used it, I've always been shocked with how quickly I run through those little tubs and how much I'm spending on it.  This time, I'll be fairing with microballoons.  Hopefully, it will cost me a little less and still provide those great results.

The last time I priced quickfair it was within $5.00 of a similar amount of S3 epoxy.  Now comparing to the Bateau Marine epoxy its kind of pricy.  at 1.5 gallon kit of quickfair is $136.00 and the epoxy $93.00. 

[Ray Frechette Jr]

Quick fair buys you time.. And when you build for hire,  time is money...

With quick fair not only can I sand it down and recoat it faster,  I also need to recoat it less then when I use microballoons.

Microballoons sag after spreading and distort.

Quickfair holds it's shape untill cured.

Yep,  It sure is pricey though.

Time savings does make it worth it for me though...