Sanding between coats

[Rand]

How important is it to sand between coats of minwax polyurethane?

The directions say to let the coat dry for 3-4 hours and then lightly sand with 220.

Has anyone ever skipped the sanding between coats and had bad results?

[ragswl4]

Some may say its overkill, but I sand between coats with 400 grit wet/dry on jewelry boxes and the finish comes out like glass on the 3rd coat. Poly doesn't stick to itself very well unless its roughed up between coats.

[cabinetman]

I always sand between coats. What grit you use depends on how the last one looks and feels. You don't want to roughen it up to the point that the next coat has to fill the scratches on what you sanded. The first sanding I may use 320 open coat. Wet sanding is more fail safe, but in any case allow for the coat to be sanded to be thoroughly dry.

Not sanding will telegraph any imperfections to the next coat.

[Jeffrey Schronce]

Depends on how many and type of imperfections the first coat may have. If you have a flawless first coat the I would say it would not be problem to apply second coat w/o sanding.
I have not had the experience of poly not sticking to itself, however I usually use a higher solvency poly thus promoting adhesion.
An additional question here is are you using water or solvent based poly? Is it straight poly or thinned with MS or Naptha?

[radhak]

The very first time I used poly for finish 2 years ago, I skipped in-between sanding totally, and applied 3 or 4 coats of poly. I still have that piece of wood, and I can't think of anything uglier. There are bumps, zits, and whatnot. It taught me to be extra diligent about sanding now.

My advice - if you don't like to sand, then, umm, well, grin-and-do-it.

[cabinetman]

The very first time I used poly for finish 2 years ago, I skipped in-between sanding totally, and applied 3 or 4 coats of poly. I still have that piece of wood, and I can't think of anything uglier. There are bumps, zits, and whatnot. It taught me to be extra diligent about sanding now.

My advice - if you don't like to sand, then, umm, well, grin-and-do-it.

This sounds like a case of workers' remorse. I agree with the "grin-and-do-it" philosophy. A lesson well learned to know the steps necessary in any project and follow them. There are some projects that have some short cuts. On any particular project there will be steps that can be challenging and interesting and remind you that you are woodworking (like hand cutting dovetails), and then there are steps that are just a repetitious bore necessary for the process. It's all in appreciating the completed piece and at that time all the steps seem very inconsequential.

[L. D. Jeffries]

To add my 2c: I usually start out with shellac, lightly sand, then poly, sand with 220 or higher, then another coat of poly. Let that really cure/dry, then wax with Butchers or something equal using 4x steel wool. Result: smooth as a baby butt! Anyway, works for me.

[lcm1947]

Hey L.D. if you are still around? Why the Butchers (wax)? and how do you steel wool it? I mean do you use it applying a circular motion? Like compounding a car for example?

[Rand]

Thanks for all the responses!
I recently bought a 42" plasma so of course I had to build a shrine to it. I designed and built an entertainment center out of oak plywood with solid oak trim. There are several mistakes in it but the most ambitious woodworking project I've ever done.

If my calculations are correct there is about 112 square feet of surface to finish. After sanding, vacuuming, tack clothing, staining, tack clothing, brushing on a coat of oil based poly I was looking for a shortcut. After reading the first couple of replies to my original post I went out and sanded it. You shamed me into it!

Thanks, it looks pretty **** good if I do say so myself.

Rand

[kdaustin]

Sanding

I normally use about 000 grade steel wool for my between coats sanding. It isn't actually sanding but it comes out nice. I also use tack cloth as the steel wool tends to shed as I use it

Ken

[JimD]

Poly and varnish so not normally disolve the previous coat. Shellac and lacquer do. You will get good adhesion with shellac or lacquer without sanding - if the previous coat is smooth you can shoot it again. I always sand poly, regardless of brand, at least a little for adhesion purposes.

Jim

[SARGE..g-47]

I wet sand the first coat with 400 and wet sand the second with 600. If I have end grain, I seal it with shellac before I apply stain or poly if poly is the weapon of choice. I use poly only for kitchen and bath projects normally, unless young children are heavily exposed to the furniture and then the poly again gets the call.

Regards...

[L. D. Jeffries]

Well I guess the reason I use Butcher's is cause when I was in the 8th AF NCO Academy; it was an automatic gig if you used liquid polish on your rooms floor..the one's who were smart said "Use Butcher's", so I did with great results. Just a hold over from the ole days I guess. Anyway it works good on most all kinds of surfaces. As far as the 4x steel wool; just make a pad and rub it in the wax, then nice circular motions to apply-let it day and buff with old t-shirt or something. You wind up with a hard surface that is sooo' smooth!