Same Paint for Wood and Metal Parts?

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Model T Ford Forum: Forum 2016: Same Paint for Wood and Metal Parts?
Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Tuesday, January 26, 2016 - 12:06 pm:

My wife is the painter in the family and I'm sure she'll do her homework before purchasing materials, but I thought I'd get some thoughts from the community.
Restocreating a WWI Light patrol Car which will use a 1915 T frame and fenders, a 26/27 engine, but the body will be an all wood open light express body.
The frame will NOT be black, but OD lusterless green, the same as the wooden body.

Would you use the same type of paint for the metal parts as well as the wooden ones? Same primer? Of, the same shade, but different chemistry?

I'll hang up and listen.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dick Fischer - Arroyo Grande, CA on Tuesday, January 26, 2016 - 03:05 pm:

The key to your question is the "substrate" -- metal versus wood.

Wood expands and contracts with moisture changes. That expansion/contraction process eventually breaks the bond between the wood and its coating. So many paints that work well over metal don't last long over wood.

Wooden exterior doors on houses are a prime example of the seasonal moisture expansion and contraction effects. How long does the paint last on such a door ?

If you keep your car indoors, will the paint still peel due to expansion and contraction ? Well, it will last longer, but the humidity in the atmosphere is enough to eventually start cracking and peeling.

The key is to moisture proof the wood. That means coating all sides of whatever part that you're working on. It also means that the moisture proofing product should penetrate deeply into the wood so that the surface is dimensionally stable.

One of the best ways to provide a stable substrate when painting over wood is to first coat the wood with a fairly thin, slow setting epoxy resin. The epoxy soaks into the wood and forms a fairly moisture proof, stable surface for any subsequent paint. It may take more than one application of epoxy if the wood is very porous. Then, when you apply your paint topcoat, you are really painting plastic rather than wood.

Dick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Tuesday, January 26, 2016 - 05:33 pm:

The primer we used on our 42 GPW was a two part epoxy primer. One coat of opoxy on the treated metal, one coat of high filler primer, sand smooth, a 2nd coat of epoxy primer and then three coats of OD lusterless green.

So we would be leaning towards the same two part epoxy primer on both the metal and wood.

I understand your analogy of the wooden door on my house. For that reason, I do not use the same paint on the wooden door as I do on the iron fence rails. Might be the same color, but two different technologies. Enamel vs. latex, oil vs. water, oly vs enamel, varnish vs lacquer. etc.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Donnie Brown North Central Arkansas on Tuesday, January 26, 2016 - 05:58 pm:

Robert, I would highly suggest to use kwick-poly to seal all the wood. inside and out. It soaks deep into the wood and turns the top layer of wood into almost like a fiberglass skin. I have never had anything fail when using it. The main thing is have all your ducks in a row and work very fast, almost to the point of being sloppy with it. You have maybe 3 to six minutes before it "kicks" and hardens almost instantly. It does sand well , so the surface finish does not matter. You are using it like a heavy primer coat. Langs sells it in their catalog. If you choose to try it. I would do a couple small tests to get the feel of how fast it sets up. In my personal opinion (worth very little) there is no other choice for wood. The two part primers will work great over the Kwik poly. But a two part primer by itself over wood will probably fail before too long. Try the Kwik poly, you will like it ... (no I do not own stock in the company :-) :-)) Its just like a miracle fix it all product in my shop .... have fun and be safe Donnie Brown .....


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Tuesday, January 26, 2016 - 07:02 pm:

And do both sides of the wood, otherwise the un-finished side will "breath and warp the finished side.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Tuesday, January 26, 2016 - 09:15 pm:

And do both sides of the wood, otherwise the un-finished side will "breath and warp the finished side.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Tuesday, January 26, 2016 - 09:20 pm:

Well, that's just weird; I log back into dial up and it posts again! And, of course, when I go to "Delete post' it says my username/password doesn't match! It matched to get me to my profile!!
also, the word was supposed to be "breathe"
David


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Tuesday, January 26, 2016 - 09:50 pm:

Does the quick poly leave a clear wood grain surface? One of my wife's concerns is to coat the wood with some sort of sealer or finish that, if the next owner did not want a WWI military vehicle, the OD green could be removed or sanded off and get to a bare wood surface for finishing.
Seems like the two are opposing views, get a good durable finish that will stay and yet, allow to be removed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dick Fischer - Arroyo Grande, CA on Wednesday, January 27, 2016 - 12:49 am:

You should be able to sand off the color paint and leave the epoxy substrate intact. Most epoxies are clear or slightly amber.

I've never used Kwik Poly, but others have and think highly of it. K-P is very thin and achieves its penetration in spite of the short cure time. Other epoxies may be higher viscosity but penetrate well by virtue of a longer cure time.

Gougeon Brothers is a manufacturer of epoxy resins that are used in wooden boat construction. You might give them a call (toll free) at 866-937-8797 and ask to speak to a technical advisor. You'll find a world of information on the very subject that concerns you.

Dick


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Wednesday, January 27, 2016 - 03:28 am:

Quick poly has a yellow color to it, it is not clear.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Killecut on Wednesday, January 27, 2016 - 07:45 am:

I have saved a lot of original T wood with K-P. The hardest thing is making a form or dam to hold it as it is liquid until it hardens.For the first line of defense I use electrical tape,then gorilla tape over it,If you use the gorilla first K-P will leak through the adhesive. I also use 3M strip calk.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Brough on Wednesday, January 27, 2016 - 10:03 am:

The two part epoxy 3m primer that we used on the 42 GPW can be purchased in several colors to assist with the top coat. Either red oxide or we chose a grey shade. We'll look into a clear version of it.
Our intention would be to construct the light open express body in sections like the bench seat, flor boards, dash, rear utility bed, tailgate, etc., and paint all wood prior to final assembly. We might at least prime or coat all pieces of wood prior to assembly and then paint OD green. But no bare wood exposed at all. \
And, this vehicle will probably be a garage or museum queen.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dick Fischer - Arroyo Grande, CA on Wednesday, January 27, 2016 - 11:47 am:

Robert, the two part epoxy 3m primer isn't the same thing as a true epoxy resin. The primer won't soak into the wood in the same way that a simple resin will. Also, epoxy primers aren't entirely moisture proof. That's why the instructions almost always tell you to put the topcoat on within a limited number of hours or days.

You really need to "embalm" the wood if you want a stable surface to paint over. The 3m primer would be an excellent primer under the final paint, but only if there is a truly soaked-in treatment as a base.

Dick


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