Finishing questons


Hello,
I am in the process of making bathroom cabinets using veneer core mahogany plywood for the carcass and solid oak for the doors. The doors will have a couple of strips of the mahogany inlaid into them.
To simplify the work I am installing the (solid mahogany) trim on the carcass panels prior to assembly. Carcass assembly is by biscuits, screws and glue.
I have been reading a book on finishing and they recommend the use of a pore filler for open grained woods. Mahogany and oak are specifically mentioned. Doing this to the doors should not be a problem but I figure using pore filler on assembled carcasses would be a royal PITA.
My questions: Can I (or should I) pore fill the mahogany prior to assembly? It would certainly be easier than trying to use pore filler on the inside of the cabinet after the fact! What affect would this have on the strength of the glue up? I expect I would also have to stain the wood prior to filling it as well. Would this cause any issues? Finally, Would there be any issues applying the final finish over the pore filler? I plan top use satin polyurethane since a bathroom is a pretty humid environment.
Dean Hummel
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<snip>

Have you decided what you are going to use for pore filler? There are various types, which can and will affect the finish you put over them. But that's why you choose, right?
One of the last several issues of Fine Woodworking had an article on 'old school' pore fillers, which seemed pretty authoritative. And the woodworking stores have various concoctions on their shelves, too.
But whatever you choose, you ought to be able to fill the panels prior to assembly. Some folks even get a couple of coats of finish on early as well. Heck, some of us cheat and buy prefinished maple and/or birch plywood, and build the cabinets out of that. It won't look like yours should, when you're done, but the clients are happy.
If you're worried, tape off the glue joints with blue or green tape, or leave the panels a bit large, and trim after pore filling.
Good luck. Practice on scrap. Take pictures. Smile.
Patriarch
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Can't really answer your question, but before you do it, I suggest you do a scrap piece with and without filler. If you don't have previous experience with it, you might just find you don't like it.
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Dean Hummel says...

Filling the pores is always optional. You don't have to do it and most mahogany and oak is finished without it. It's mostly done on fine furniture, especially table tops where a mirror finish is desired. The satin polyurethane isn't going to highlight your laborious job of filling the pores very well. Do yourself a favor and forget about it. The cabinets will look great without it.
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Dean Hummel wrote:

All a "pore filler" does is fill in the grain so that,as previously mentioned, you can obtain a mirror like finish. The smoother the finish the higher the gloss. Using a satin poly, you can achieve the same effect by applying several coats and sanding down with fine paper between each. When Shallac (French Polish)was the most popular finish a grain filler was almost always used as this a thin product and would require a hell of a lot of coats to fill an open grain type timber. With most modern finishes this is not required. Hope this helps you out a bit. All the best John
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Dean:
I made a walnut case recently, and searched for and found hardwood filler and used it. The damn wood looked like plastic it was so smooth. Not a happy camper.
What I have done now (mostly on lathe turned stuff) is to not fill it, but put a first coat of wiping varnish on it, let it cure. Then I put on another coat, and wet sand it with the varnish as the wet, with 220 or 320 grit. (Don't use the black silicon carbide paper, you get black grit! I use the 3M "super paper" can't think of the name now.)
What you end up with is a slurry of wood dust, and varnish that fills the pores somewhat, and looks like the wood, but leaves the nice natural texture. After that dries, you do need another light sanding to get it smooth, before your final coats. I've used this on oak and walnut, both quite open pored woods.
If you don't know, you can make very good wiping varnish with half varnish, half turps or paint thinner. I use a lot of MinWax Tung Oil finish, which is about the same thing.
As always, try it on a scrap to see if you are happy with it. See the first paragraph for why.
Walt C

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Lot's o' good advice. Filler is typicially only used on furniture and is VERY difficult to get right.
Don't fill, don't put too thick of a coat of whatever and you'll still be able to feel the wood and be very happy.
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Thanks for all the responses. The consensus seems to be not to use pore filler. I have used an oil based (dark brown) pore filler on an oak desk chair I refinished some time ago and was satisfied with the results. The end finish was VERY smooth (final coats were a high gloss varnish that was wet sanded with #0000 steel wool to bring it back to a smooth satin). If you are really hung up on the wood texture then this is probably not for you. I will try this on a scrap piece before I make my final decision.
This does lead to another question. How advisable is it to stain and put a sealer coat on (50% mineral spirits, 50% varnish) before carcass assembly? Again this would be easier than crawling around the inside of a cabinet but I do wonder about glue up issues...
Dean Hummel
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I think you could stain/finish the inside with whatever you want as long as you mask off the areas that will be glued with some good-quality masking tape (that won't leave residue or pull up fibers). Sounds a lot easier than staining/finishing inside corners to me!
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