Interior Wood Treatment

[Podunkfla]

Okay, I have a question...

Do you have to use a stain first to seal the wood and then MW spar urethane? Or does the spar urethane also seal the wood??

I have been doing some testing today on scrap with the spar urethane with and without the stain. I got mixed results, on one piece I did just the spar urethane and it got to dark for my liking, then on another piece it turned out perfect. I'm trying to keep it light, but I bought some light pecan stain just in case I have to use it to seal the wood. I'm using birch BTW.

Any help is appreciated!!!

MK

EDIT, OH and can you use spar urethane over tung oil? I love the way tung oil pops the grain out, but I dont know if the spar urethane will stick and stay on it???

Thanks again. Mk

MaryK... The Minwax Stain (or most any stain) is not much of a sealer. It wasn't meant for that. Most stains are nothing more than solvent, with a little bit of something to act as a binder, and pigment for color. Most shades of Minwax also have some dye as well as pigment. A sealer should actually seal the pores in the wood so any additional coats of finish do not soak in at all. Tung oil, Antique Oil, Boiled linseed oil, and most other oil finishes are not really sealers either, although if you use enough coats they eventually do seal pretty good. You can put spar varnish and even polyurethane over these oil type finishes as long as they are dry... It's done all the time.

Helmsman and most all "spar varnishes" have a distinct amber color. If you seal the wood first with something that has very little color the spar varnish probably will not change the color as much as you're seeing. Like Miriam says, they do make clear finishes that will work too. The least colored are automotive clears. One of the oldest and still one of the best sealers is shellac. Most of the big-box stores now sell premixed shellac in quart cans. It comes in both clear and amber. You thin it with denatured alcohol. You can wipe, brush or spray it on and it dries very fast. It works good as a sealer over stains and dyes. It can also be used as a pre-stain sealer to keep end grain and woods prone to blotching like pine and cherry from absorbing too much stain in some areas. You just thin it a lot like 50 to 75 percent.

One small caution: If you are using polyurethane as a topcoat, make sure you get a "dewaxed" shellac. The Bullseye Shellac they sell in cans dosn't tell you weather it is dewaxed or not (?). But, the clear is dewaxed; the amber isn't. http://www.zinsser.com/product_detail.asp?ProductID=31

As I've mentioned here before... It will prolly save you a lot of trial and error to invest in either Michael Dresdner's or Bob Flexner's book on the subject: Amazon.com

Hope this helps some...

friend ~ Brick

[tk]

If you use shellac, check the sell-by date before purchase. Outdated shellac won't dry hard. In extreme cases I think it won't ever harden completely.

Tom

[b.bodemer]

This is a great thread....


I finally decided on Helmsman Spar Varnish in a satin finish. I also had some Clear Shield in satin finsih that I used in the galley. As mentioned the spar urethane gave a nice warm look to the wood, both my oak sides and birch top.


Barb

[48Rob]

Hi Phil,

Something to consider regarding spar urethane is that while it does contain UV inhibitors which are important for exterior finishes, it also has the ability to flex, that is to move with physical changes in the wood caused by expansion/contraction due to temperature and humidity changes.

On the exterior of a wood sided trailer, this is good.
For the interior of a trailer, it can also be good, but with a price to pay.

In order to be able to flex, the finish must also be soft...

Not a bad thing, but sometimes a harder, more durable finish is more realistic for interior, or galley spaces?

Rob

[Miriam C.]

One small caution: If you are using polyurethane as a topcoat, make sure you get a "dewaxed" shellac. The Bullseye Shellac they sell in cans dosn't tell you weather it is dewaxed or not (?). But, the clear is dewaxed; the amber isn't. http://www.zinsser.com/product_detail.asp?ProductID=31

Brick, I called Zinsser and asked about using shellac as an outside coat and they told me it wouldn't flex enough for use on a Teardrop. Said:"it would harden and crack." I asked because I specifically wanted the warm amber color.

[Mary K]

Thanks every one for your replies.

Mk

[Mary K]

Okay, so I just jumped right in it today. I found that the spar urethane went on darker when I used a brush and lighter when I used a lint free cloth. So, I stared with the first coat with the cloth, a real light coat. It was dry in 2 hours. Then I sanded that really good and put a second thicker coat on with a good$$$ brush. It will be dry, I hope by 8 so I can sand with 120 grit and another coat with the brush. Then I will get up early, sand, and apply another coat before work. I'd want to do 5 coats, is that okay???

I hope I didn't do the wrong thing with the cloth, but it looks good so far.

Oh and I have some Minwax Polyshades for the interior. It was free... but I might try the Formby's Tung oil, I have 2 cans of already... This is all so confusing really and I can not pinch out the $ for that book you suggested Brick.

I really appreciate all the help I found in this thread and others.

Mk

[Podunkfla]

One small caution: If you are using polyurethane as a topcoat, make sure you get a "dewaxed" shellac. The Bullseye Shellac they sell in cans dosn't tell you weather it is dewaxed or not (?). But, the clear is dewaxed; the amber isn't. http://www.zinsser.com/product_detail.asp?ProductID=31

Brick, I called Zinsser and asked about using shellac as an outside coat and they told me it wouldn't flex enough for use on a Teardrop. Said:"it would harden and crack." I asked because I specifically wanted the warm amber color.

Miriam... I haven't had that experience with Bullseye shellac (or any other dewaxed shellac I mix from flakes either)? Maybe it doesn't crack because I only use enough to fill the pores of the wood? I probably also sand most of it off getting the wood smooth before I do the topcoats. I apply multiple topcoats of marine spar varnish over it. The varnish is the real wood protection and good spar varnish is quite soft and stays flexible a long time.

Sooo... As much as I would like to accept the Zisser's tech peoples advise they gave you; I will have to go with my own experience using the product. I am also basing my view on a lot of other woodworkers that I know that also use shellac as a sealer for boats and other wood projects that do see the outdoors. Are there better products to use? Probably, new stuff is being created all the time... I just don't know about them all yet. I have also used sanding sealers from Sherwin-Williams and Benjamin-Moore with good results too (they just dry too slow for me). I'd be interested to hear what one of the real finishing pros like Flexner or Dresdner, that know a lot more than I do, has to say on the subject?

Of course, Since this thread was entitled "Interior Wood Treatment" I was mostly thinking of an answer that applied to that area.

For the exterior of a tear I would much prefer using epoxy resin and fiberglas cloth on the top, then topcoat it spar varnish with UV protection... and just epoxy/spar varnish on woodie type sides.

[Miriam C.]

Brick, I only asked if I could use it as a top coat. I guess it didn't occure to me or them to varnish over it. I sure would like to have used it as a color. Where were you way back then?

[Tripmaker]

Okay, I have a question...

Do you have to use a stain first to seal the wood and then MW spar urethane? Or does the spar urethane also seal the wood??

I have been doing some testing today on scrap with the spar urethane with and without the stain. I got mixed results, on one piece I did just the spar urethane and it got to dark for my liking, then on another piece it turned out perfect. I'm trying to keep it light, but I bought some light pecan stain just in case I have to use it to seal the wood. I'm using birch BTW.

Any help is appreciated!!!

MK


EDIT, OH and can you use spar urethane over tung oil? I love the way tung oil pops the grain out, but I dont know if the spar urethane will stick and stay on it???

Thanks again. Mk

No stain does not seal the wood. Stain soaks into and stain's or colors the wood. One exception to that is some of the "one step" stain and seal products that are available.

If you are trying to keep it light I would not use stain. I would think that any stain would darken the wood. You can make light wood dark but can't make dark wood light with stain as you are coloring the wood, not covering it like you would using paint. There may be ways to bleach wood to lighten it but that's beyond what I know about.

Getting the color you want can be difficult as almost anything you put on it will darken the color somewhat. Even the sanding sealer I used darkens the wood, in my case birch. Trying to match colors between different types of wood compounds the problem. Even the same type of wood reacts to stain or coatings differently depending on the grain. I'm using poplar for my face frames that tends to have a slight greenish tint to it. I've decided to not use any stain and just use the sanding sealer and spar urethane. The difference in color between the various woods makes it interesting. Let the natural beauty of the wood come through.

Not sure about using urethane over tongue oil. My guess is no, that the urethane would not react well with the oil but not sure, experiment on scrap and see if it cures OK. You might try using a sanding sealer as that brings out the grain and is designed to work with urethane.

[Podunkfla]

Oh and I have some Minwax Polyshades for the interior. It was free... but I might try the Formby's Tung oil, I have 2 cans of already... This is all so confusing really and I can not pinch out the $ for that book you suggested Brick.
I really appreciate all the help I found in this thread and others.
Mk

MaryK... I don't like or ever use Polyshades... It just never looks good for me. Since it is polyurethane with color pigments added, it is very hard to get it even looking... and then it just looks too much like plastic? Your tung oil would prolly be easier to use cause you can just wipe it on till it looks good. It does dry kinda slow, so usually you only get on about a coat a day. You could then topcoat it with Minwax Wipe-On Poly (or a poly you thinned to wipe on consistancy yourself). Pretty much a foolproof way of finishing.

As for Flexner's book... You can get it used on Amazon for $8.07 & $3.49 shipping...
Holy Cow, $11.56 shipped is pretty dang cheap??? Prolly cost more for a trip to McDonalds for your Happy Meal er whatever?

Understanding Wood Finishing by Bob Flexner: http://www.amazon.com/gp/offer-listing/ ... F8&s=books

(So... I finally learned how to put a picture in my Sig... And I chose the stupidist lookin picture I could find?)