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Please critique my finishing schedule

1K views 15 replies 12 participants last post by  OSU55 
#1 · (Edited by Moderator)
First time working with walnut.

Application: writing desk with maple base, walnut top. SWMBO has declared her intent to place wine glasses, water glasses, and coffee cups on the top, so a durable finish is needed. I prefer a flat (not glossy) finish. I do not wish to stain or dye the wood. I also do not need a "piano like" finish and while I would like a nice end product, I would rather not spend more time than necessary drying things.

Plan

1) ROS sand to 220

2) wipe on BLO to pop the grain, add some amber color. Wet sand by hand with 220. Goal of wet sanding: create a slurry to fill the walnut grain

3) wipe off excess across the grain [so that slurry isn't removed]. Let dry 4-6 hours

4) hand sand with 320 just until smooth

5) repeat 2-4 using 400 to wet sand and 400 or 600 after drying

6) possibly repeat a third time

7) apply a satin water-based polyurethane after the BLO has thoroughly dried.

Questions

1) Do I have to fill the grain of walnut or is that only necessary if I were going for a "piano like" finish? If "no," can I just do a single coat of BLO to pop the grain and then move on to poly for protection? Or a poly+BLO 50/50 blend?

2) Should I instead use a BLO + oil-based urethane blend and eliminate step (7) ?

3) Is the entire finishing schedule needed on both sides of a table top? What can I omit on the underside?
 
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#4 · (Edited by Moderator)
Personally I don't really like the look of filled grain wood. It no longer looks like wood that way… more like plastic with a wood pattern printed on. I like to finish walnut with an amber shellac sealer coat followed by a mid-satin varnish of some kind. And 600 grit is extremely high for regular finishing. 220 or 320 is plenty high enough for a poly finish. I'm no expert, though… try experimenting and come up with your own technique.
 
#5 ·
Not sure what you mean by "wet sand". If that;s using the BLO as a lubricant, it will work just fine. Water, maybe not so much. You could also use wiping varnish, or a danish oil. Personally I wouldn't bother filling the grain on walnut, but that is a bit of a personal preference thing. Also question the sanding to such a fine grit. My approach would be to use a garnet shellac for the color (BLO is great, but be sure to let it cure before applying a waterborne top coat) and then top coat the shellac with a good waterborne finish…probably one of the GF products. My first choice would be an oil based varnish, that would be P&L 38, but I can't find it anymore and the waterborne finishes are very good.
 
#7 ·
You'll need to at least match the number of coats of each finish on both sides, or risk uneven moisture loss. You could sand less on the bottom if you don't care how flat the finish is. If you fill the pores, fill both sides as well.

Brian
 
#8 ·
I always recommend the same thing for finishing. Test on scrap, and see if you like the finish. Sand some parts to 150, other parts to 600, and see what you think.

I've done this, and I thought sanding finer did help in the end product. Your experiments might lead you to a different conclusion, though.

I don't think there is much of a benefit to multiple BLO applications, as the finish doesn't 'build' anyway.

Regarding your last question, yes, you will want to finish the underside of the table, just to control how ambient moisture enters the wood (because even with a finish, moisture still gets through). I think you can get cupping if you finish only one side of the wood.
 
#14 ·
The "grain popping" is caused by the oil in a finish. Some time back a guy named Michael Dresdner (a finishing guru in the eyes of many) wrote an article claiming that any oil based varnish has the same effect as an application of BLO (appearance wise). His point being that if you use oil based varnish, skip the BLO…just added work/effort for no gain. I won't dispute his opinion, but it is just that: opinion. All of this is more easily solved with the test on scrap routine and see ow it appears to your eyes. Shellac enhances the grain with color (that's why I like the garnet on Walnut).
 
#15 ·
Why not do a wiping varnish? If you are looking for the richness of oil, don't complicate it with water based poly which can make darker woods look washed out.

I think BLO takes a long time to dry as well, a nice wiping poly will give you the same look you desire in way less steps.
 
#16 ·
I've tested Dresdner's, and Bob Flexner's, information concerning oil based poly or other varnish providing the same look as BLO, and it is accurate information. Varnish will provide the "chatoyance", grain pop, i.e. reflective properties of the wood same as blo or shellac. The color of the varnish impacts the finished color/look of course. Here is more info on the subject. Don't use marine/spar varnish for indoor use - the higher oil content simply results in a softer finish that takes longer to cure.

Leftcoaster, if spraying the finish, WB poly is a good choice - I like Target EM9000. I recommend getting some Transtint Honey Amber to mix into whatever WB poly you use. The WB finishes can take on a bit of a bluish, or some pinkish, hue and the TT gives a color more like oil based varnish. If brushing/wiping, use ob poly. The wb finishes set up too fast, especially for something as large as a desk. If you use ob poly, you don't need the shellac to pop the grain.

I like to color walnut, usually a medium to dark brown color. Especially kiln dried walnut can have a grayish tint and the color warms it up.
 
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