Teardrops n Tiny Travel Trailers

OK here goes.. I read somewhere here that when building a Woodie that one should spar varnish the sides before putting on the trim. OK so here is the question. What glue would you use ? It would have to stick to the finished varnish on both sides. I have been using Titebond 3 on everything. If you use an epoxy what epoxy. Thanks guys La Tortuga moves on.

Based on the title of the topic, I kind of thought this thread would be XXX rated.

Anyway, I've been a hobbyist woodworker for decades and it's my opinion that you should never glue wood to varnish. It should always be a wood to wood glue joint. A lot of the strength of a glue joint comes from the surface you are glueing to and in the case of varnish the strength would be the thickness of the varnish and how well it is adhered to the wood. Varnish does not adhere to wood nearly as well as glue so it would make a very weak joint. I'm no expert so take this with a grain of salt. Just my 2 cents.

Ed

Hi Red,

That may have been me?

I (strongly) suggest to all who ask my opinion that any applied/attached trim pieces (wood on wood) be varnished or otherwise encapsulated to provide moisture protection on all sides and edges.

This means if your trailer has wood sides and you attach wood trim to the sides, all the parts should be sealed well BEFORE attaching them.

If you screw a piece of wood trim to the side of your wood trailer, and then seal or varnish all, there is a very high probability that moisture will get between the pieces.
Once moisture gets between them, it will go into the wood and discolor it under the finish.
Then the finish itself will peel/flake off.

If you choose to glue wood trim to a wood panel, then seal or varnish the works, you MAY be okay if you get 100% coverage of the two mating surfaces.
The glue acting as a sealer/waterproofer.

The caution I would give with that scenario however, is that plywood being a manufactured product, and trim being a natural product, will expend/contract at different rates, which could cause the glue joint to fail allowing water into the wood.
This will have the same effect as clamping two unfinished pieces together, and hoping that water won't penetrate.

Of course you can/could just attach the pieces any way you see fit, then caulk all the joints.
It might work...
However, when the time comes to apply a new coat of varnish/finish to the trailer, all that caulking must first be removed...

Creating wood projects for the home isn't all that difficult with regard to moisture protection, but when you build wood projects that will be exposed to the elements, if proper precautions aren't taken, most will begin to fail very quickly.

When varnish fails, it is rarely a case of "scuffing it up" and applying a fresh coat.
Most often the wood will discolor first, then the varnish will flake and peel.
At that point, the entire project will have to be stripped down past the varnish and stain, the wood sanded to remove the discoloration, and new stain and varnish applied...one heck of a big job!

Rob

RD, my first question to you would be...what type of finish are planing on doing on the exterior...I would highly recommend an epoxy finish covered in either an auto clear or spar urethane...and I agree with Rob as well......if you use epoxy to attach your trim and then finish with epoxy, you have the same material for glue up and finish...if going this way, keep in mind, some epoxies don't play well with some oil based stains...as far as recommending an epoxy, I sure like the stuff from www.raka.com ..................
madjack

The one thing that stands out with Rob's explanation is the "screws". If you are using mechanical fasteners then you will be fine covering all the surfaces first. I used epoxy and then used epoxy for the glue.

I was going to say the same thing an aunty M. If you mechanically fasten the pieces to the body, then no problem finishing all sides first. The problem is that you don’t want to put the varnish in tension (actually it is good design practice never to put any kind of adhesive in tension). With epoxy or some other adhesive, you get a structural bond and since the trim isn’t so far offset, you also have little tension; still, points are well taken about the difference in thermal expansion between the different wood and it would seem difficult to get a perfect seal between the body and trim. The idea of coating both sides and mechanically fastening the trim to the body seems rather appealing. You have to touch up the screw holes, but that doesn’t seem like too big of a price to pay.

OK it seems epxoy is the answer . Admiting that I have not yet read the user manual from Raka and am looking for a quick answer from those that have actually done it. Does it brush on? How hard is it to do on vertical surfaces? and how much would I need for a 5X8 tear. I promise I will read everything before I start just looking for a quick answer

kennyrayandersen wrote:I was going to say the same thing an aunty M. If you mechanically fasten the pieces to the body, then no problem finishing all sides first. The problem is that you don’t want to put the varnish in tension (actually it is good design practice never to put any kind of adhesive in tension). With epoxy or some other adhesive, you get a structural bond and since the trim isn’t so far offset, you also have little tension; still, points are well taken about the difference in thermal expansion between the different wood and it would seem difficult to get a perfect seal between the body and trim. The idea of coating both sides and mechanically fastening the trim to the body seems rather appealing. You have to touch up the screw holes, but that doesn’t seem like too big of a price to pay.

You still adhere the trim to the sides. I covered the trim with epoxy and then epoxied it to the side. I also built up dams of epoxy at the seams to keep water from my lake out.

...first, read the manuals...RAKA's is fairly simple and straight forward...West systems has a bit more info...use foam brushes and rollers, a roller will give you better finishes especially on vertical surfaces...GET THE PUMPS from RAKA as they give measured amounts and the ratios are geared to certain number of pumps...epoxy doesn't stick to most plastics so butter bowls will work for mixing...plastic paint trays for the roller...peel the setup epoxy from the pan/bowls afterwards and reused...brushes and rollers CANNOT be reused...de-natured alcohol works well for clean up...if it gets on your clothes, it will be forever andda couple of days...work with small batches(16-24ozsMAX) at a time, you can usually work out two batches(back to back) before it is time to toss it all...did I say, read the manuals...since for all practical purposes epoxy has an infinite shelf life and it good for all sorts of things, don't be afraid to buy and have leftovers go bad...start with 1.5gal kit of their non-blushing epoxy...this will go a long ways, especially if you mix up no more than you can use at one time...it ain't cheap...it has about a 30-40min work time, is tolerant of cooler temps and is fairly forgiving...apply additional coats in less than 24 hrs to avoid having to sand, or if over 24hrs lightly sand before applying additional coats...3 coats minimum, 6 is better...go thin, don't try for heavy coats on a vertical surface...it will run/sag right off the sides...take the time and material to do some practice, it'll pay off in the end...don't forget what I said about incompatibility with oil based stains...there, you asked for quick and dirty and that is about as quick and dirty as I can give it...and did I say to read the manuals.......
madjack

p.s. Doug has a link to the manuals in the stickies at the top of this section.........MJ

Also...make sure that all the exterior corners are eased on your trim. A hard/sharp 90 whether under epoxy or whatever finish, will want to split at that point and allow moisture in. Just what I've experienced. Doug

Steve, if the joints are not going to be tight you can add a thickener to the epoxy to help fill in small gaps. A thickener helps prevent dry, weak, joints where most all of the epoxy soaks into the wood surfaces leaving little to fill in the gap.

The only big problems I had with Raka epoxy were when I got the mix ratios off, usually with too much hardener, and it stayed soft. I strongly second the suggestions to get pumps so the resin and hardener are measured more accurately.

Also when "glueing" using epoxy don't clamp it as tightly as you would with a regular wood glue or you might get a "dry" joint that will be weak.

When I "glued" (epoxied) a 4'x8' sheet of birch to the inside of a sandwich wall framework I first brushed epoxy to both surfaces. Let it soak in awhile. Then I made up a thicker mix of epoxy to act as the glue and brushed it on one surface. Then clamped and/or put weight on the plywood. Left it alone to set up for a day or so.

...yep, like I said...read the manuals and follow directions...thar's reasons for them words!!!!!!!!!!!!!!!

Thanks everybody . Mad Jack that is what I was looking for I will definetly read ,study the manuals before I start. But with you explanation it doesnt seem so scary. Thank You all

RD, I am certainly no expert...not even close, but it is not as hard to learn the techniques as it may seem from afar...epoxy resin, compared to what they sell in the box stores as fiberglass(polyester resin) resin is a breeze to work with...dive on in...the Kool Aid's fine
madjack

p.s. are you going to use a stain...epoxy works better over a water based stain or an aniline dye(may or may not be available in your box store)...allow to dry, QUITE WELL and you should have no problems...call RAKA or whoever you use to find out about compatibility over a particular oil base stain...epoxy is not generally UV proof and needs to be coated with a UV protectant...either an automotive clear or a spar urethane........MJ

MJ the only experience I have was years ago with poly resin.Messing around with surfboards and stuff That is where the fear comes form. Raka sounds very doable thanks for the help