Oak and polyurethane

[gwyneth]

The only experience I've got with oak and finishes was removing about a zillion layers of paint on a gazillion feet of oak trim in a historic house that was trashed by the frat it was rented to...and then after all that work, my goofy mom had it covered again with white paint!

Flash forward a decade, I can finally stand being around oak again and have a bunch of planks to work with. But info about finishing it seems contradictory.

I know it's 'open-pore', and sealing it is suggested. With what? I've got a mixture of red and white oak, and I don't intend to stain or color it--just want to cover it with poly, probably water-based.

One finishing guru says shellac can go under poly, another says it can't. One says you can open the pores with mineral spirits, let dry, then sand and seal.

I've also got some oak veneer plywood to add to the mix.

Any and all thoughts on finishing oak would be really appreciated...

[leehljp]

On oak, I really like oil based poly. I have used water based poly on Oak but I personally did not like it but my daughter does. It is a personal preference. The oil based poly gives it a hint of amber color and gives it "warmth" in my opinion, but of course my daughter would disagree with me.

[gwyneth]

I have a bunch of both water- and oil- based, so that's a good idea. In fact, I'd thought of the oil-based for my "faux Mission" BT cart because I vaguely remember that it's supposed to be more durable.

It's the prep that confuses me, though--the pore-raising, the sealing, etc.

Some of this white oak, when planed, seems so hard and smooth that I'm wondering about the sealing step. Some of the red oak does seem pretty porous.

But what do people use to seal it? I saw one reference to very thin shellac, which would be good because I have a lot of flakes as well as a bunch mixed up that would be good to dilute and get rid of that way.

Is 'filling' a separate step from sealing? I think the terminology may be what's confusing me, as well as not understanding how a filler wouldn't look like, filler.

Thanks!

[Ken Massingale]

Use Zinsser Sealcoat as a sealer. It is dewaxed shellac which is fine under poly. Some 'guru's' claim regular shellac will cause poly to not adhere well, others say that's bunk. Another benefit of Sealcoat is that fewer top coats will be needed since the Sealcoat prevents the poly from absorbing into the wood. I find it works especially well on Red Oak.
On the White Oak it may seem hard and smooth but there may be softer spots. When you apply poly it will absorb more into the softer areas than in the harder areas, that causes blotching. The Sealcoat dries quickly so it doesn't add much to the total finishing sequence. As poly, I wipe the Sealcoat on with a soft cloth. If the project is large do 'small' areas at a time. If it starts getting tacky as you apply it, thin it a bit with DNA.
Good luck.

[MikeMcCoy]

I just finished 6 cabinets with a mix of red and white oak for the doors and face frames. I just used amber shellac and the shellac tint blended the two woods just fine.

[cabinetman]

This is the kind of question that can't really be answered easily. When I started out, there wasn't much data available on characteristics and properties of species of wood. Representatives from the different manufacturers of products would visit shops and explain their products and leave whatever limited printed material.

Red Oak, Mahogany, Maple, Ash, Cherry and Walnut were the predominant species that most hardwood suppliers carried in stock. Of those, Red Oak was the least expensive and most used. There was also the need to have the hardwood plywood in 3 thickness, 1/4", 1/2", and 3/4" available to go along with the solid wood stock for furniture building and cabinetry, and general casework.

Finishing will depend on a lot of factors. In my case it depended on the "bang for the buck" saying in that, the dollar value of the job. The time allotment had a lot to do with planning the finish, and the intended use.

One of my principles learned early was to keep like chemicals together. Any loss of time or quality due to mistakes in preparation, choice of materials, application, or delays represented a loss of income. In other words, the job comes in and has to go out.

And getting to the answer to the post. Red Oak is an open pored wood, unlike White Oak. But generally speaking the smoother it is sanded the less absorbent it becomes. The type of finish procedure will determine what you want the wood to feel like and look like. The finish can be as simple as progressively smoother stages of sanding and just a series of applications of the same finish material.

For example, the smoother and denser you want the coating to be the more of it you have to add. There are no real shortcuts. There are simple ways to do the finish.

As for film like finishes, shellac (alcohol based), varnish (oil base), oil based polyurethane (oil based - resins different than varnish), water based polyurethanes, lacquer (acetone based), are just a few general categories you could use. For most finishes, sanding the bare wood, and applying several coats of the perspective finish, sanded between coats will provide the degree of finish depending on the extent of prepping, time sanding and series of coats.

For your use, the procedure would depend if you have a spray system or you will be brushing or wiping on the finish.

Then there are degrees of initial sealing and preparation that would include types of sealers applied before the finish coats. For open pored woods like Red Oak and Mahogany, the use of a "paste wood filler", or also called "grain filler" can be used to fill the pores and soft areas of the grain, eliminating a great deal of the sealing process. It is a bit labor intensive, but done correctly will produce an absolutely glass like look and feel.

That same appearance can be achieved with several coats of either oil based product or waterbased and wet sanded to a high number and rubbed out with compounds or pumice and rottenstone.

You can achieve a very high degree of finish with shellac by applying several coats, wet sanded to a high number and then waxed.

In this reply I'm not addressing staining, or an oil or lacquer finish.

So, basically without getting it confusing , it boils down to the steps to a finish which are prepping the wood, and applying the finish. The extent you go to in the basic steps will determine the outcome.

You should try three samples. A shellac sample, an oil based polyurethane sample, and a water based polyurethane sample. In doing a complete finish with those three mediums you might come up with which one you find the easiest to use and provides the look and feel you're after. Those three can be applied without spray equipment. If you become familiar with the procedures for each, and follow the necessary steps without rushing, your finishes can become predictable.

[SARGE..g-47]

Good morning gwyneth...

Oak is open grain.. very open grain. The way to fill the grain is with paste filler which comes in light.. dark. natural. Natural can be dyed to best match the color of the stain or effect you want. And yes.. it is a process in itself of filling it.. letting it dry enough to scrape it.. then another filling if necessary. After completely filled.. you sand it to get any excess off of everything else but the pores you filled before proceeding with stain.

You can use paste to get contrast on purpose. If you wanted a zebra-wood (striped) look on white oak.. you would just use dark paste instead of tinted natural or light as normal for white oak

But.. you want the natural color to come through! That would be hard to fill without getting a definite un-wanted contrast to the filler. You basically fill when you want a very smooth.. glossy look as in "more formal". I don't use poly except in kitchen and bath furniture where I need a very hard surface and one that will keep the most moisture out.

Below I will show you a picture of a recently done break-fast table and chairs in the country farm style my wife loves at this point in life. Being an "in-formal" design.. but I don't want deep open pore spots you can physically feel on the surfce So.....

I chose poly for the hard surface in a kitchen and it's moisture barrier. I lay the first coat of oil base ( I want the amber glow it gives to natural) relatively heavy and basically un-cut as the frist coat is nothing more than to fill the pores without coloring to see them but give a smooth flow of the hand being run across the surface.

Let it dry completely for a day or so and sand it so that there is nothing left but the poly in the pores. If they didn't completly fill.. re-apply and sand again. Once you have filled the open grain with poly.. you can apply a second cost to cover and I use a 70%p-30%ms mixture of wipe-on I brew in a clear plastic kitchen bottle. Let it dry completely and then sand it with 400 wet paper with mineral sprits as a lubricant.

Now the real finishing begins with wipe-on poly cut to 60%p-40%ms. After each coat I let it dry completely and then sand with 600 wet with MS as the lube again. This will at least get 3 coats of top finish and could be as many as 5 more coats (the table has 5 added after the intial two coat to fill and cover) depending on how hard a surface you want.

That's just how I do it and will let the results speak for themselves and you can form your own opinion if you might be interested in using the method as it has been long established that I am a much better mechanic than beautician!

Regards...

[gwyneth]

Wow. Great info, and thanks.

Cabinetman, I know there's no specific answer to my questions (they were pretty open-pored themselves)...and you did a great job telling me more.

Sarge, that is one beautiful table--you're being modest.

Mike, Ken, and Lee--thanks. It's this kind of 'experience reporting' and comparing notes that makes this such a great place.

It was options I was looking for and I appreciate the time you all took to report them. Thanks again.

[Jeffrey Schronce]

Executive Summary : Use Transparent Water Based Grain Filler, then poly.

There is a lot of good info in this thread. Here's my $.02.

Oak typically has relatively deep grain or pores, particularly Red Oak. If you put 4 coats of wipe on poly on the surface you will see little indentations where the open grain is located. Many folks find this to be offensive in fine furniture as they want a super slick and even surface. This feeling runs particularly strong in regards to the surface (ie table top, desk top, etc. Many folks leave the legs, stretchers, etc with the open grain for character.

I believe filling the grain is an excellent idea for surfaces. As noted in other posts, there are many types of grain filler. BTW, grain raising really has nothing to do with filling pores, rather it is a process typically involved with water based products. I struggled with grain filler for quite some time. Color matching, contrast, etc always took a lot of work. Then I found JA Mosers transparent water based grain filler. This stuff is awesome. Takes tints if you want to go that route, but you can leave it plain transparent and it works GREAT with oak products. In short, it is my answer to your question. This is what fills the grain. No need for shellac prior to applying. Use poly after for durable finish. I used water based poly after using it due to cabinetmans theory of keeping like chemicals together. Solvent based poly may be fine once grain fill is cured but I didn't want to risk it.

Another person on this forum has recommended Enduro Water Base Grain Filler availible at Homesteadfinishing.com. I have not used this product, but I have used a lot of products from this site owned by Jeff Jewit. If he is selling it, then its good enough for me.

[gerti]

So you don't want to use white paint? :devil:

[gwyneth]

So you don't want to use white paint?

Part of my 'oak catharthis' therapy involves sharing some of the painful details.

Serving as the contractor on the job of repairing the damage left by the frat/athletic team (almost six figures worth!), I spent my "off-hours" that summer on the optional task of uncovering the oak woodwork.

This included, but was not limited to, a "square arch" section between two rooms that was 3 ft. wide, 12 ft. high, and 24 ft. long.

The house was then about 100 years old and it had probably been almost that long since the first of many layers of paint had been applied.

Evenings, I'd drag out the ladders and platform system, put on the visor-helmet and lie on my back to do the top of the arch. (Next time anybody has to strip wood, just think--you could be doing it overhead, 12 ft. up.)

When I left at the end of the summer, it was all done except about a foot near the floor on each side, with only parts of two layers...one hard day's or two evenings' work.

Visiting at Christmas, I was walking by and noticed the shiny white surface through the windows.

In a way, it was the perfect punchline for the whole job (some of the original destruction still makes me laugh, like the man-shaped hole in the plaster wall at the end of one room).

[Jeffrey Schronce]

So you don't want to use white paint? :devil:

Hey, I really like your blog/webpage! Nicely laid out! Good info.

[gwyneth]

Jeffrey--thanks so much for taking the time to write up the executive summary. I had no idea that clear filler existed.

The site you mentioned was about the only useful info a couple of Google searches produced before my original post, but I found only the coloring recipes and didn't look around further. They do seem extremely knowledgable.

Gerti, you do have a nice site. Even though your inquiry about the white paint made me spit some coffee out, its therapeutic value (concerning my issues with oak) was high.

Thanks, everybody.

[JimD]

gwyneth,

I am not sure how much I can add but I cannot help commenting. I am sitting in our family room with two end tables and a coffee table made of red oak. In our breakfast room are a table and four chairs of red oak. In the entry way is a mission style table of red oak. Our bed, end tables, cabinet and entertainment center are all red oak. I have built a few things of oak.

I have used oil based poly but I rarely use it anymore. Some like the amber cast but I don't. Probably most of the furniture I've made of oak has been finished with Minwax water based poly. I have put it on with a brush (often foam), a roller, and I've sprayed it. It takes a month to reach full hardness but otherwise is pretty nice. Because it does not sand real well I often use a sanding sealer for the first coat. The last few things I've built have been finished with Resisthane, a water based pre catalyzed lacquer. It works best sprayed and sprays easily. It dries in an hour and sands very well. It needs no sanding sealer. It is thinner than poly, however, so on oak 4 or 5 coats is necessary IMHO. At an hour a coat, that is not so hard to achieve. 3 coats of poly seem like enough.

Barrels are made of white oak because the pores do not run all the way through - they are plugged every little bit. Red oak has pores that run through. White oak tends to be somewhat grey sometimes. I like the really red color of red oak heartwood so that is what I try to use.

I do not try and make oak smooth. Doing so on boards would take a lot of work. Oak plywood takes less finish than boards because there is not much thickness to the oak veneer. I sand between coats but I do not use a filler or wet sand which would fill the pores. I just get enough coats on the surface so that it is sealed but it still has indentations at the pores. To me, that is what oak is supposed to look like. When I want a real smooth surface, I use cherry or maple.

Jim

[gerti]

Gerti, you do have a nice site. Even though your inquiry about the white paint made me spit some coffee out, its therapeutic value (concerning my issues with oak) was high..

That's how it was meant... I could understand how seeing that white painted arch could have brought tears to your eyes! Never had much use for painted wood myself. I guess there are places for it, but if I can avoid it I will.

And thanks to you and Jeffrey for the compliments! Have not had much time recently to work on either web page or in the shop. But I'll get back to it eventually.