Ok this is my first furniture piece so forgive my ignorance. I made a kitchen island out of cherry and finished it with Olympic oil based "Natural" stain (pretty much a clear stain)and then put on my first coat of polyurethane. I am going to let that dry overnite, but I hear several instructions on "sanding between coats". Does this mean sanding with an orbital sander with what grit paper? something like 600 grit? Also how many coats of polyurethane should I use? thanks!!
It means light hand sanding with 220 or thereabouts. NOT power sanding. If applied in typical fashion (thickness), three coats is typical (assuming you aren't thinning the finish much).
I tend to use 320 more often than 220, as I spray water borne urethane, instead of poly. You can recoat poly under "normal" conditions in less than 3-5 hours, btw.
Since poly does not normally go on with additional coats being applied over tacked coats - you put coats on over dried coats, you will want to simply scruff the surface for adhesion and smooth spreading. Steel wool, 3M pads or sandpaper ranging from around 320 grit on up will work. All you are looking to do is break the glaze on the dried coat for the new coat to adhere to. While you're at it, know down any dust nibs.
If you're spraying it then experiment with spraying additional coats over tacked up coats. Obviously, you would not sand between coats since the tacked up coats will not sand very well. Smear would be more like it. I've had mixed success with spraying poly so I generally just brush it with a light rub down between coats.
Poly usually has a "window" for recoating. If you recoat before this window ends, usually 4-6 hours, you don't need to sand. If you miss it, you'll need to wait 24 hours, and scuff sand before recoating.
To me, "scuff sand" usually means 320 grit, using hand blocks and tadpoles. I might carefully hand sand with 220 if there are large dust nibs or brush marks to be removed. If the finish "pills" on the paper, which is small balls of finish appearing on the paper vs. a clean dust, wait longer to sand.
As for number of coats, it depends on the look you're after. Thinned poly, wiped on, may need 4-6+ coats. Brushed on, full strength stuff may only need two. Too much usually makes for an artificial look, too little may leave uneven spots.
Wiping on usually makes for a much more natural look. You can thin standard oil-base poly 20-40% with mineral spirits to make it wipable. Wipe it on with a clean piece of old t-shirt, which can be stored in a jar or zip-lock for the duration of the project. If you wipe a coat on every 4 hours or so, sanding will not be required.
It helps to make a scrap board and do EVERY finishing step, including the same sanding sequence, to the board before the work piece. Write every step on the back as you go. Problems will then show up on the board before you're hard worked furniture.
Last comment: If you're looking for a satin finish, only use satin poly for the last coat. Use gloss for the early coats. Satin and semi-gloss clear finish include "flattening agents" that can cloud a multi-coat finish. Gloss finishes build without killing clarity.
On most of the can of Poly it says to re-coat within a 2 hour time frame. More importantly, it also states that if you miss that window, you have to wait 72 hours before sanding and recoating.
I wait the 72 hours, sand with 400 - 600 wet using mineral sprits as a lubricant, dry, wipe with a clean lint-free towel dampened with mineral sprits let dry then re-coat. I probably would not go to that much trouble for a kitchen cabinet however. I would put on two or three coats all within the 2 hour time frame. Let dry for a few days, touch up bad areas with 600 or 000 steel wool and spray(can) recoat.
72 hours between coats, huh? You've got a LOT more patience than yours truly! :) I'm chomping at the bit after 2 hours to get the next coat on (waterborne), or 3-4 hours when using poly (ugh).
From: snipped-for-privacy@sherwin.com Subject: RE: Minwax.com: Contact Us
Dave,
As long as the conditions you're working in are good, you can recoat within
2 hours (the product will most likely be dry enough within an hour unless humidity is too high or the temperature is too cool, lack of air circulation, etc.). As long as you hit the recoat window, the aerosol version is different in that you will get a chemical bond between coats. If you don't hit that window, the finish will skin over or cure enough on the surface, so if you were to try to recoat at that point, the new coat would cause the one underneath to wrinkle. This is why we suggest allowing the finish to cure for 72 hours, then create a mechanical bond by lightly scuff sanding before applying the next coat of the aerosol version, if you're unable to hit the recoat window.
Why on earth are you quoting Minwhacks??? No where did I mention my application of Minwhacks products. I HATE Minwhacks, AAMOF. Most other mfgrs produce superior finishes and stains.
David, The point was, read the instructions. The poly I used on the last project said wait 72 hours before sanding. If the OP (or anyone else reading this post) was using Minwax Spray Poly, then sanding after only a few hours would raise havoc with their project.
AAMOF - really a fact or just your humble opinion. IMHO, Minwax makes a good product for many applications. I will grant you there are better ones out there and I have used many of them. The use drives my decision on the product choice.
I've sprayed Minwhacks and had no problem sanding after 3 1/2 to 4 hours...but I reserve my right to use non-Minwhacks products from now on. :)
As to the "AAMOF" that you mention, I was stating an absolute "FACT"; that I hate their products. That is not opinion, nor subject to interpretation, or spin by you. My last comment about other products was, indeed, my humble "opinion".
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