Opinions on Lacquer Finish

I've turned a dizzy bowl using 10 different wood species and because of how the pieces are oriented, much of it is end grain. I'm finishing with Deft gloss lacquer and I am not happy with the results so far. The picture will hopefully show the low shiny spots after 3 coats and a light sanding with 400 grit. A couple of questions I'd like to throw out there are; should I continue with what I started (2 or 3 coats followed with progressively finer grit sanding) and if I do, how many coats of Deft are going to be too many?? I mean, if 15 coats are needed to fill the low spots will that many coats create a problem later? Also, would another brand of lacquer be better and if so, would it be compatible with Deft?

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I would have started with a celluose sanding sealer. Its lacquer based and would fill in the grain faster. Also no need to sand between coats of lacquer the thinner in it softens the previous coat to bond to it.

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Originally Posted by Richard Madden

I've turned a dizzy bowl using 10 different wood species and because of how the pieces are oriented, much of it is end grain. I'm finishing with Deft gloss lacquer and I am not happy with the results so far. The picture will hopefully show the low shiny spots after 3 coats and a light sanding with 400 grit. A couple of questions I'd like to throw out there are; should I continue with what I started (2 or 3 coats followed with progressively finer grit sanding) and if I do, how many coats of Deft are going to be too many?? I mean, if 15 coats are needed to fill the low spots will that many coats create a problem later? Also, would another brand of lacquer be better and if so, would it be compatible with Deft?

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There are several different kinds of lacquer and each has a little different procedure. The deft lacquer is a type known as nitrocellulose lacquer. The resin for it is made by dissolving cotton in nitric acid. It's an easy to use lacquer and very forgiving. Now like a cotton tee shirt yellows as it ages so does the lacquer made from it. On light colored wood, ash for example gets to looking pretty bad when the finish gets old. Working it, it doesn't build a thickness very quickly though. This is what a lacquer sanding sealer is for. Think of it as a clear primer. You build the finish with sanding sealer sanding between coats until you get the appearance you like and then topcoat with lacquer. Another down side to nitro lacquer is it isn't very water resistant. 30-40 years ago it was commonly used as a finish for kitchens but because of water damage at the sink other finishes are used now.

Then there is a cab-acrylic lacquer sometimes called butyrate lacquer. It works much like nitro lacquer but will remain clear. Because of the yellowing of the sanding sealer it's best to use a non-yellowing sealer such as a vinyl sealer. It just doesn't build like a nitro sealer but will remain clear.

Then there is pre-catalyzed lacquer. It's a non-yellowing lacquer which uses the vinyl sealer. It's more water resistant because it contains a hardener. You have to watch the date of manufacturer in a lot of places. If the hardener is added at the factory they date the can and it has about a six month shelf life. Some places mix the hardener in at the time of purchase which gives you more time to use it.

Then there is a fully catalyzed lacquer. It's very much like the pre-catalyzed lacquer only it uses a stronger hardener which you mix yourself as you use it. Once mixed it usually has a shelf life of about eight hours. You would also use the vinyl sealer with it so it would remain clear.

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Originally Posted by Richard Madden

...I'm finishing with Deft gloss lacquer and I am not happy with the results so far. The picture will hopefully show the low shiny spots after 3 coats and a light sanding with 400 grit. ...
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Richard,

Hard to tell from the picture but to me it looks like you have two things going on, one, open pores from the end grain of ring porous woon such as oak, and ame tearout.

Unless I WANT these to show in the final finish I never use lacquer until the surface is perfectly smooth with no voids, what you called low spots. Open pores can be filled with a grain filler. They are typically applied with a plastic squegee, forced into the pores, then sanded after dry. Many are colored dark or lighter to match the wood somewhat but these might leave obvious dark spots on light wood, and vice versa. There are clear grain fillers that will be invisible on any color of wood - I have some but can't remember the name right now and I'm not at home.

If you have tearout, it should be managed before sanding. For wood and orientation prone to tearout best is to recut the surface with an extremely sharp gouge, ofted best done after applying a few coats of lacquer or shellac based sanding sealer, thinned with solvant. Then make a very light finish cut, perhaps smooth with a negative rake scraper, sand, then repeat as needed. However, this may not be feasable with your piece if it's aleady been removed from the lathe.

Some people will power sand with coarse paper after the sanding sealer to remove tearout and flatten the filled surface. I don't do that but instead use well sharpened hand scrapers and fine sandpaper (by hand, often wet sanding). Either way, I make the surface perfect one way or another before applying the first coat of lacquer. (After that, i may apply 6 or more thin coats, smoothing with 400 to 1000 grit paper between some, 0000 steel wool, and perhaps pummice and rottenstone depending on what I want it to look like.

If you do have a little remaining tearout in a few places, there is a trick I learned from John Lucas: wet sand with CA glue! This works surprisingly well for isolated spots. Apply a bit if thin CA to some fairly coarse sandpaper, say 220 or finer, and sand the bare wood by hand. This will deposit and glue fine sawdust from the surrounding area into the voids and fill them to the surface. Then seal and sand/finish as usual.

If you can't get it smooth enough, maybe someone who does a lot of segmented turning will have good suggestions. Perhaps ask at a club meeting.

As for just applying more coats of lacquer and sanding between each, this may eventually work but may take a lot of coats. For sanding the surface without dipping into small voids I wrap the sandpaper around a white "Magic Rub" eraser and sand by hand. I think starting with the clear grain filler would be a lot easier.

JKJ

Thanks for the advice, John. While at the local Woodcraft yesterday and questioning the guys there about the finish, I was shown a product called Aqua-Coat, a clear grain filler. Maybe this is what you were referring to. I'll look on their website, but would you know if Aqua-Coat could be used over what finish is there, or should it sanded down completely.
I also use stiff foam rubber to back up the sandpaper.

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Originally Posted by Richard Madden

Thanks for the advice, John. While at the local Woodcraft yesterday and questioning the guys there about the finish, I was shown a product called Aqua-Coat, a clear grain filler. Maybe this is what you were referring to. I'll look on their website, but would you know if Aqua-Coat could be used over what finish is there, or should it sanded down completely.
I also use stiff foam rubber to back up the sandpaper.

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Yes, Aqua-Coat was what I was thinking of. I've never tried it over lacquer, you might try a test. Maybe the instructions would tell. I'd personally be inclned to remove any existing buildup on the surface first. I'd probably try hand scrapers for that instead of sandpaper.

JKJ

Dyas's info is spot on--very good info on using lacquer--have sprayed a drum of the stuff over the years--one addition though, Sandind sealer come in many different qualities--I use Mohawk's heavy bodied SS, brushed on straight for 2 coats--this will seal and fill like a (filler ) all the pores--most SS are thinner and require several coats--sand down to smooth and shoot lacquer like a pro. I' ve had very mixed results with Aqua coat--your mileage may vary.

John has given good advice. I might add that Deft High-gloss has more solids than regular semi-gloss and they can cause problems. You can get just as glossy an appearance with semi-gloss by wet sanding with polishing papers or buffing the piece.

The only Deft I have used is labeled--brushing lacquer? Any semi-gloss lac. is softer than gloss--an additive that be bought and added. Rattlecan lac. if by definition very thin on solids to allow for the low pressure and tiny orfices on RC. Brushing lac. is thinned with thinner and retarder to assist flowout after brushing. Retarder is simply a slow-drying thinner which also helps prevent blushing on high humidity days.