May I please get some topcoat advice?

[Mark Rios]

I'm putting putting the finish on the pieces that make up the sound studio console that I working on. The cabinet pieces are black with a Min-Wax spray poly clear satin finish. The top surfaces are edge-banded African mahogany plywood. I have BLO on the top surfaces.

After using the Min-Wax product on the cabinet parts, I'm not very enthusiastic about using it on the BLO finished mahogany.

May I get some recommendations for a topcoat please? The main desk top will have glass over it (at least that's what the owner is saying that he will do) but there is approx. 10 sq. ft. (distributed between 3 pieces) of other top surface area. One of the surfaces will have a flat panel monitor sitting on it and all of the top surfaces will be used like a desk top, stuff being set on them and so forth. Is there an easy to apply yet hard and durable topcoat for this?

Thanks very much for any help and advice.

[Jim Becker]

What specifically are you concerned with using the MinWax product on the rest of the project? Was this a "spray bomb" or did you use a gun? Do you intend to shoot for a glass-smooth finish on the mahogany or is it fine for the pores to show through?

[Mark Rios]

Thanks for your reply Jim.

Working backwards, yes, the pores are fine showing.

The product was from a spray can, spray bomb.

After applying three coats of the Min-Wax and letting it dry for two days, I needed to mask on it. To test it first, I applied 1" 3M masking tape to a test piece (finished the same way and at the same time) and let the tape sit for 5 hours (+/- a few minutes). Then I removed the tape and some of the clear came off. It also didn't seem to be all that durable for a table top surface.

I was wondering if I should get a Min-Wax wipe-on poly. I've never used it but it should go on heavier. Or should I just apply more coats of from the spray can? Should I be using a product that dries harder?

Thanks again for your help.

[Don Baer]

Mark,
I'll be using General Finishes Polycrylic as a top coat for the desk I'm building for LOML. I put it on a test piece and realy love the look. It's water based and a coat dry's in about an hour. I put 4 coats on the test piece Sanded between coats with 400. My grandaughter has beat it with a hammer. She dented the wood but the finish stayed intact.
It's easy to use, just apply it with those cheap foam brushes. Clean up is a snap.

[Jim Becker]

Please keep in mind that anything with polyurethane in it hates to stick even to itself. That's why you need to sand between coats...to give "tooth". Unfortunately, that's not practical with the thin coats you get when spraying and likely one of the reasons your sprayed on finish came off with the tape...in addition to the fact that it really needs to fully cure before you do something like that. A full cure takes weeks...

The only project that I've used poly on in recent memory is our kitchen table. Frankly, I'm unhappy with it as it's degrading big-time with the frequent cleaning it gets...much to my surprise.

My personal preference these days is water borne finishes, usually from Target Coatings. My preferred application method is spraying, although there is a method detailed for applying USL with a quality brush. It sounds like the product that Don recommends can be brushed, although I caution about foam brushes as they can add bubbles to the finish way too easy. A high-quality synthetic bristle brush made for working with water borne finishes should give great results, but be aware that these finishes tend to "dry" quickly. In fact, you may need to use an approved retarder for brushing them.

Another option is to use a "regular" oil-based varnish, thinned a little, with a brush. If you are happy with the oiled mahogany's current tone and want less color change, use something like Pratt and Lambert #38, an alkyd varnish formulated with soya oil. I think that Varathane has a similar product available now. These have less "amber" to them as the oil is lighter in color.

[Don Baer]

Jim,
The manager of my local woodcraft is the one who recommended the Polycrylic and he also recommended using the foam brushes. I raised my eyebrows when he recommended the faom brush and he assured me that there would be no bubbles. There were no bubbles on the test piece just like he said there wouldn't be. He also told me NOT to shake the can, stir it gently he said otherwise I would get bubbles.

[Jim Becker]

Good deal, Don. I've always had trouble with foam brushes so I only use them with house paint for touch-ups at this point. Maybe I'll try it again sometime with WB, although I generally spray it.

[Jim W. White]

I'll second Don's experience that foam brushes work very well for the water based poly. In between coats (or projects for that matter), I simply wash the brush out under the faucet, dry with a paper towel, and put it in a ziplock sandwich bag in the refrigerator; it works great!!

While I've had good luck with the water based poly, for this application I think I would go with a topcoat I've had great luck with in "heavy use" applications. General Finishes Arm-r-Seal. It is an oil based poly but it flows extremely well and makes a rock hard finish.

Jim in Idaho

[Mark Rios]

Here is a picture of the full plywood sheet,

11ply.jpg

Here is the desk top and the shelf top,

12ply.jpg

They are just finished with BLO now. I was able to find a brush on Varathane product. I'll do a test and see how it looks.

Thanks for all your help, and anymore help/advice is very much appreciated.

[Kyle Robinson]

I've had good luck with wipe-on poly that I make myself; just get regular gloss poly and a plastic cup, dilute it with either naptha or mineral spirits. I use about 30% mineral spirits, naptha would dry faster. The advantage of making my own is I know how it was diluted, and by how much. Use gloss because it doesn't have any particles in it; commercial products get a satin look by adding particles to mute the shine. I can get a satin finish without blurring the finish just by polishing the gloss finish with #0000 steel wool.

I just wipe on about 4-5 coats, and to wipe it on I wear disposable gloves and just use an ordinary heavy-duty paper towel. I fold it up, wet in in the solution, and wipe it on like I was trying to wet the surface. If the towel starts to wear, toss it and use another piece. The thin coats dry relatively quickly, so I can apply 2 per nite about an hour or so apart. Then I let it dry for a day and repeat.

I get a durable finish with no runs or sags I need to polish out. I used to brush on poly and then I'd spend a lot of time "finishing the finish" with various wet/dry sandpapers and so on. Now it's simplicity itself. Let the finish harden for a week (more if you have the time), then get some #0000 steel wool and some wax. Dip the steel wool in the wax and use it to rub off any dust adhering to the finish. This also produces a nice satin finish.