Wood Sealer - Water Based vs Oil/Poly

[WhitneyK]

I'm not sure who the original "chemist" was on this site that gave the formula for the economical wood sealer = 1 part polyurethane & 3 parts mineral spirits. And that's neither here or there. I know Rod (rlowell) has recently mentioned using it. I like the idea as am considering using it myself.

However, on my way to work, while pondering on some of life’s perplexing issues, questions, and mysteries, I had this thought (didn't say it was a good one)(kind of like one of those throne room thoughts I guess):

Instead of polyurethane/paint thinner, has anyone tried the water based poly thinned with water to the same ratio?(or so) If it would work, it would be more user friendly, easy clean up, less toxic (like that matters to some of us), reduced odor; short term & long term, quicker drying time?

Cons: could rust hardware (screws, staples, etc) if SS or galv fasteners weren't used

Any thoughts on this?

If this thread turns out to be a dud, feel free to kill it and get rid of it.

[Deryk the Pirate]

ok, isnt the solvent suposed to help remove water(dampness) thats in the wood...while the epoxy or varnish/polyurethane seals it. You wouldnt want to seal wet wood the rot process would happen for sure.

[Rlowell]

That is the way that I understood the situation. With the poly and paint thinner formula the wood is dryer and you are sealing the wood all the way through. The idea is to get a "complete" seal on the wood. What ever else you do is basically window dressing. My 2 cents. That is how I did it.

Good luck,
Rod

[GPW]

I'd stick with the mineral spirits ... won't swell the wood ... Besides the Min. is innocuous ...

[Shadow Catcher]

I am trying to hel friends who have an 04 Chalet Aframe trailer that has an OSB floor that is failing (rot). My understanding is that in 05 Chalet went with a composite floor so they knew they had a problem. I joined a Chalet Aliner e-mail group and I am learing what went wrong and how to fix it. In doing the research I have encountered the http://www.rotdoctor.com and an understanding of CPES.
Yes expensive but looks good. One quetion, how much is your trailer/labor worth? How difficult would a failed floor be to replace?
I am a firm believer in using a resperator or gas mask and have a couple of surplus gasmasks I picked up on ebay, but if you are working outdoors with plenty of ventelation it is probably not crucial.

[GPW]

SC , being a modeler for many years , have seen people develop sensitivities to epoxy products ... A modeler friend was rushed to the hospital with what he thought was a heart attack ... turned out was his long term epoxy exposure ... Which he does not use anymore...

I'm sure CPES does a great job sealing the wood , just prefer to use something less potentially dangerous... and Lots cheaper too ...


I'm mixing up some Min/poly today to coat my unsealed TT OSB floor and repair ... something that was missed/omitted at the factory (What were they thinking ... or not ??? ) grrrrrr!!!!

[Rlowell]

CPES is talked about all over this forum and everyone seems to have great results with the product. At a price...plus shipping... The poly seal mixture
has been around for much long and was used on airplanes and many other proven products....and is much cheaper and you don't have to wait for shipping. I have invested $13 to seal my build. And I rant...sorry

Rod

[48Rob]

Hi Whitney,


I'm not sure that any chemists came up with this particular formula?

What it amounts to is using a "sealer" (something that seals the wood you are applying it to).
Paint and varnish have long been used to seal.
If the material is fairly thick with pigments, it tends to adhere just to the surface of the wood, okay if you are applying several coats to build up thickness/protection.

When you are working with raw or untreated wood, thinning the paint/varnish with the same solvent used in the material, you are literally making the mixture "thinner".
Using a much thinner mixture of the paint/varnish allows the material to penetrate much deeper into the wood.
This helps to protect the surface from minor cuts, scrapes, abrasions that would otherwise have allowed moisture to get under the applied layer of paint/varnish, and cause peeling, discoloration, and ultimately rot.

Applying a thinned mixture is not the end of the process however, as it is just a very thin layer that has penetrated a little ways into the wood.
Several more coats of the same material need to be applied, using standard finishing techniques such as cleaning and sanding or scuffing each layer after they are completely dry, to give the next coat something to grip.

Encapsulation, that is the goal.
If you do not/can not completely encapsulate the wood, you are better off to do nothing to your raw wood.

Some people use a thinned mixture of varnish, and then apply several layers of paint, which can work too.

Would water based material work?
I haven't tried, but if you could ensure that the wood was 100% waterproof when finished, it should.

Historically, oil based paints and varnishes have been much harder/abrasion resistant than the softer water based materials, meaning that rock chips, etc could perhaps penetrate the softer finish, leading to a better chance of water damage.

That said, on all my trailer projects, once I have the (bottom) wood encapsulated, I treat it with several coats of a rubberized automotive undercoating material, to provide extra protection.

On the exterior of my wood bodied trailer, undercoating would have spoiled the look, so I chose to add extra layers of varnish.
I check the finish carefully each time we're out camping and immediately touch up any nicks with clear fingernail polish to prevent moisture from getting under the finish, and every couple years I clean, scuff it up, and apply another coat of varnish.

A lot of work, but encapsulated is not encapsulated if there are holes in the finish...

Rob

[GPW]

Rob , I can trace the poly/min mixture back to Chuck Felton and his airplanes (waterproofing common cardboard) ... That's where I learned about it , and have used it with much success for many years now on all manner of projects .... You're Totally right ! LOTS of coats !!! It's cheap , so ... Soak it in !!! Guess I'm trying to turn the wood into plastic , fill all those little tubes with something more water resistant ... In our extreme Humidity here, things tend to be soaked for a long time ... so I seal the wood , then paint over it too ... As you said , Total encapsulation is the Goal !!! If the water can't get in , it can't Rot eh ....


COOL that Nail polish trick!! ...

[Deryk the Pirate]

Just out of curiosity do you have to let the varnish/mineral spirits dry between coats or could you brush on 4 or 5 coats let it dry flip the wood and do the same thing to the other side?

thanks

[Deryk the Pirate]

and would you be able to epoxy over it if need be?

[48Rob]

Hi Deryk,

Water based, or oil based, each coat needs to completely dry before applying the next coat.

Rob

[GuitarPhotog]

What are recommended brands of polyurethane? Can I use Varathane with mineral spirits to seal the wood?

<Chas>

[48Rob]

Hi Charles,

Varathane is a brand name, polyurethane is a general description.

As with anything, there are different levels of quality to suit the buying market...

For deep penetration of raw wood to begin the encapsulation process, pretty much any thinned polyurethane will work.

For the final coats of protection, a higher quality material might be a better choice, though more money tends to buy you more pigments and UV protection.
If you are coating the underside of a trailer floor, or walls that will be covered with paint or aluminum, it probably isn't worth the extra expense.

If you are doing a wood bodied trailer where the wood will be exposed to view, buying good varnish ($100 per gallon and up) and using the same product all the way through the finishing process, from thinned to final full strength coats is the best plan.

Rob

[GPW]

Robs right , let it dry thoroughly between coats , BUT when I put on a coat , I really SOAK it Good !!! The first coat just sucks up into the wood , and you'll find progressive coats make the surface much less absorbent... You COULD even tighten up the mixture (less solvent) for more effective "encapsulation" ... ^ Extra coats around the end grain is a good idea !
If I had a BIG shop , I think I'd just let all the wood soak in a tank of this mixture for a couple weeks .. Nice to have a tank big enough to drop a finished TD shell into .. ... and an overhead crane .. just wishing ... Fatuous!!!