Bondo vs formula 27 vs epoxy fairing

[xymotic]

OK, so below the waterline, top of the line splash-zone or 3M filler. I get that.

But.

I have an old steel boat, that's WAY wavy all over. Above the waterline, is there a super compelling reason not to fair using a product like this:
Evercoat

which is $16 a GALLON

Not thickly mind you, but as a final top coat.

Vs a dedicated "marine" product like pettit ez-fair or formula 27? at $20 a PINT!?

I was using a product called ez-fair that the PO had left on the boat, but it takes 4 hours between sands vs like 20 minutes for the above. It also specs an epoxy resin top coat, so I got to thinking: heck if I'm gonna do that why not use something like the above... the epoxy should seal it up, right?

[onestepcsy37]

why bother fairing it at all? below the waterline, sure. but above?

i think i would investigate the inside structure to see if maybe there is some really sinister reason why the hull plates are warping....

[xymotic]

Originally Posted by onestepcsy37

why bother fairing it at all? below the waterline, sure. but above?

i think i would investigate the inside structure to see if maybe there is some really sinister reason why the hull plates are warping....

I'm not even talking about hull plates. I'm currently working on a hatch. It had some rust, that pitted some of it, it is not quite square, and there's a little warping from impact or maybe even just oxy welding 'back in the day' (it's a 1938 boat) Then, all of that was covered with Mahogany, so I think it was not that important to start with.

But I'm redoing it, and I want it to look nice.

But the cabin has a bunch of areas that are similar. The PO did some weird rust repairs (aka 'not' repairs) and at the end of the day I'd like to smooth out the rougher edges and paint er purdy

[minaret]

Evercoat is a glazing compound, it's meant to fill pinholes and minor imperfections before priming. It sands like talc but has no real longevity, and should not be applied in thickness more than 1/8". It is much too thin for fairing. If you must use a poly fairing compound go with Rage Gold for your purpose, it is designed for use on steel hulls. But I would definitely use WEST with 407 myself. Vastly superior for a steel boat.


http://www.amazon.com/Fibreglass-Eve.../dp/B000P6URMA

[xymotic]

Originally Posted by minaret

Evercoat is a glazing compound, it's meant to fill pinholes and minor imperfections before priming. It sands like talc but has no real longevity, and should not be applied in thickness more than 1/8". It is much too thin for fairing. If you must use a poly fairing compound go with Rage Gold for your purpose, it is designed for use on steel hulls. But I would definitely use WEST with 407 myself. Vastly superior for a steel boat.


Fibreglass Evercoat 112 Rage Gold Premium Lightweight Body Filler - Gallon : Amazon.com : Automotive

I'm probably misusing the term 'fairing' There were only a couple spots more than 1/8th and I used Splash-zone there. Then I used the stuff I had on the boat, QUICK FAIR EPOXY PUTTY from Aircraft Spruce

That was OK, but I found it hard to measure out and a couple times it didn't set right in small areas. ANd that's the 4hr between applications & cover with epoxy stuff so I wasn't too impressed overall. And then evercoat on top for the last layer to get rid of really tiny divots and holes.

Hmmm, I guess with pumps West/407 would be 'almost' as convenient. Would it completely encapsulate the steel in one step or would I need to paint on a final clear coat of west with that as well? (I've never used 407) vastly more expensive though

[minaret]

Originally Posted by xymotic

I'm probably misusing the term 'fairing' There were only a couple spots more than 1/8th and I used Splash-zone there. Then I used the stuff I had on the boat, QUICK FAIR EPOXY PUTTY from Aircraft Spruce

That was OK, but I found it hard to measure out and a couple times it didn't set right in small areas. ANd that's the 4hr between applications & cover with epoxy stuff so I wasn't too impressed overall. And then evercoat on top for the last layer to get rid of really tiny divots and holes.

Hmmm, I guess with pumps West/407 would be 'almost' as convenient. Would it completely encapsulate the steel in one step or would I need to paint on a final clear coat of west with that as well? (I've never used 407) vastly more expensive though

Never apply a poly product over epoxy, ie Evercoat over Quick Fair. Personally I don't like mixing different products at all, it complicates good fairing by giving you a surface with different densities/hardness rating. 407 is actually surprisingly economical. The thing to remember is that while it takes lots of colloidal silica to get to the desired thickness, with lots of mixing, 407 or 410 thickens much faster with much less product. Also with silica the batch size stays about the same when you mix, with 407 it will double. So what I'm saying is that a fairly small pot of resin will yield a fairly large pot of fairing compound. You can make the cure time whatever you want, you can chemical bond, you can green trim, and you get a superior bond with superior moisture resistance. Sands easier too. You don't need to coat 407 with neat epoxy, you can prime it. I'd say it's actually cheaper in the long run.

[rognvald]

Xymotic, two things to consider: 1.) If the mil is not great, bondo has been used in the auto repair business since the first steel car rolled off the assembly line. It was never intended as a structural filler but rather a cosmetic filler that is easy to apply, sand and finish. I have used it for over 40 years with great results and 2.) if a greater structural application is required, there are few products superior to West System as others have mentioned. However, neither product would be suitable where torsional loads exist since it would certainly crack and/or destroy the structural bond ie: corners, bends, turns, uneven junction points, etc. I would, in either case, do a complete and thorough sanding/cleaning of the area to be faired with an eye on temperature control for the best bond. Before undertaking a major project, I would try a couple test areas with both products. There is no contest, however, when it comes to speed of repair and Bondo would be the clear winner. Good luck and good sailing.

[minaret]

For small repairs, bondo is indeed faster due to the cure times. But for a large area or a whole boat I would disagree, for the same reason. You must mix a whole lot of small batches to slick a whole hull with bondo, and the result will be ugly because you will be lapping wet fills onto cured material. With epoxy I can use a slower hardener and mix massive batches, slick the whole hull all in one wet pass, and have it look like it barely needs sanding afterwards. Way less wasted material and time, less sanding, and a better product. Ever submerge any of those cars in salt water?

[Sumner]

Most products that are of the 'bondo' type will absorb water which is why they have gotten a bad name. Guys would do body repair at home out in the driveway and then spray primer over it and drive the car at the same time. The rattle can primer wasn't waterproof and any water went through it and was absorbed by the bondo which then put the moisture at the bondo/metal interface and the metal would rust and the bondo would pop off.

I've done a fair amount of body work....

http://purplesagetradingpost.com/sum...mnerindex.html

... and use ....

Evercoat

... the Everglass above where I've welded in patch panels and are worried about moisture coming in from the back side through pin-holes in the weld. Then I'll go to a bondo like product over the everglass for the final finish work before painting.

If you use catalyzed primers and top coat with 2 part paints moisture won't get to the bondo. The problem is that if you ever develop a crack in the paint the moisture will and then you have problems again. That is what could happen in your case using a bondo type product. Then you have another big repair job or something that doesn't look good.

For your application I'd use one of the waterproof products in the link above, but there is one problem with that. Those products don't finish as nice as what you first posted so aren't really designed to go from them to paint if you are looking for a really nice finish.

I'd think about one of the waterproof ones the link I posted to get close to perfection and then use a marine finish product over that before the paint. Make sure they are compatible with each other first though. Using the cheaper one (that is waterproof) under the expensive one would save money.

Good luck and don't forget that a good looking paint job is 80% or more dependent on the work that goes under and before it. If the work under it isn't 100% perfect the finished paint job won't ever be,

Sum

[rognvald]

Bondo filler claims to have no more than 0.3% moisture absorbtion on unfinished surfaces. A proper marine primer and finish coats would undoubtedly decrease that percentage to, perhaps, almost zero. However, there is no contest that West System is superior to Bondo/Bondo like products as Minaret has stated but I think it depends on the surface area under consideration and time elements anticipated. The products mentioned by Sumner may be a better choice than Bondo and it is obvious from his website that he has considerable experience in the recon of metal surfaces. The bottom line, however, is what is your goal, how much time are you willing to devote and what anticipated results are you expecting? The previous discussions should certainly point you in the right direction. Good luck and good sailing. bondo.com/

[xymotic]

Thanks all for the help! I'm anticipating that this is going to be a job of many, many small jobs rather than stripping everything and going from one end to the other. That's probably not the smart way to do it, but that's why I really like the way this stuff applies: Mix. apply and it's almost perfect right there. Wait 20 min and sand. Vs everything else I've tried is mix... if you can get an accurate measurement of product, apply but it goes on kinday wavy and difficult. Wait half a day for it to set, if it ever does. Sand an hour, and then repeat. ug.

[minaret]

Originally Posted by xymotic

Thanks all for the help! I'm anticipating that this is going to be a job of many, many small jobs rather than stripping everything and going from one end to the other. That's probably not the smart way to do it, but that's why I really like the way this stuff applies: Mix. apply and it's almost perfect right there. Wait 20 min and sand. Vs everything else I've tried is mix... if you can get an accurate measurement of product, apply but it goes on kinday wavy and difficult. Wait half a day for it to set, if it ever does. Sand an hour, and then repeat. ug.

Yeah, you should probably go with Rage Gold then. It is the only Evercoat product specifically formulated for steel. I linked to it on Amazon above, they want $50 a gallon for it. I'm pretty sure my Fisheries rate would be much lower, if you need to buy a bunch on account let me know and I'll meet you there. I have to charge tax but my merchant account is so huge that we get an extra 6% off the usual merchant rate, which is much lower than retail for this sort of thing.

[xymotic]

the Everglass above where I've welded in patch panels and are worried about moisture coming in from the back side through pin-holes in the weld. Then I'll go to a bondo like product over the everglass for the final finish work before painting.

Thanks Sumner, exactly the kind of info I need. What primer would you recommend for the back-side of the weld? I've been coating it in Ospho, and then I get a little lost because I'm unsure if I should clean that up again, wash it or something, and then paint with a 2 part like Pettit metal prime or something simple like pettit rust-lok (which I happen to have a fair amount of on hand)

[xymotic]

Originally Posted by minaret

Yeah, you should probably go with Rage Gold then. It is the only Evercoat product specifically formulated for steel. I linked to it on Amazon above, they want $50 a gallon for it. I'm pretty sure my Fisheries rate would be much lower, if you need to buy a bunch on account let me know and I'll meet you there. I have to charge tax but my merchant account is so huge that we get an extra 6% off the usual merchant rate, which is much lower than retail for this sort of thing.

Cool thank you!! I'll keep that in mind. I think I'll try 407 just for fun as well. I work @ WM so I can get that relatively inexpensively. I doubt we carry the Rage gold though, so I'd have to spec order it and I'm sure your price would be way lower.

The worst part is: I won't know which way was best/cheapest/easiest for like fifteen years lol

[Sumner]

Originally Posted by minaret

Ever submerge any of those cars in salt water?

Yep....



....that was water at the Bonneville Salt Flats so more concentrated than the ocean, but you are right about the effect. The disk brakes came through. The rear brakes I replaced. The truck body and trailer body have a lot of bodywork problems after 150,000 miles and a couple thousand on the salt flats alone.

If the salt water can get through the outer coating to the talc body filler and the metal under it you will sooner or later have a mess. My truck and trailer need to be redone and they both had been down to bare metal with an epoxy primer on everything.

If a person can do it the method you described....

Originally Posted by minaret

.. With epoxy I can use a slower hardener and mix massive batches, slick the whole hull all in one wet pass, and have it look like it barely needs sanding afterwards. Way less wasted material and time, less sanding, and a better product...

...is by far the best solution,

Sum