Nitrocellulose Versus Catalyzed Lacquers for Furniture Finishing

      Compared to modern cabinet finish formulas, old-fashioned nitrocellulose offers more ability to fine-tune the color. June 18, 2009

I am currently finishing a couple of walnut veneered tops of which I filled the grain with a paste filler. The smaller pores did not take the filler. I have applied probably 7-10mils of gloss Gemini Ultra Lacquer over the course of three days. By doing this, all of the pores have been filled, but have left behind some small dimples/orange peel. I feel confident that my finish is thick enough to safely level, but I have never done this before to extent that I need to now. Basically my question is, how do you flatten your lacquer?

Forum Responses
(Finishing Forum)
From contributor F:
First off, 7-10 mils is too much for most pre cat lacquers, it can cause problems down the road with cracking, etc. I am not familiar with Gemini's pre cat but I would definitely check with your supplier.

As far as leveling goes you are on the right track with the grain filler and sanding between coats, the next step if you had been using a nitro lacquer would be rubbing out with steel wool or machine buffing with a rubbing compound. This is another reason not to use catalyzed finishes for this type of finish many of them tend not to rub out very well. A more modern approach is to use a 2k urethane finish from the start that is designed for thicker mil applications.

From contributor Z:
7-10 mils is way too much. Sand it all down to bare wood with an ro sander or at least down to a mill or two. Your pores will be sanded level and then shoot another mill or two max. Your 7-19 finish is going to crack anyway and you'll end up doing it later so do it now.

From contributor D:
Your dry mil thickness is way too much. Sand it back, way back. Your final grit should be 320. Then apply a flow coat of thinned precat. If you are doing a rubbed finish then start your rubbing within a few days of application. If you are going for a shoot and scoot, off-the-gun, you ought to be good to go.

Next time, make life easy: either use a lacquer-based clear filler from Hood Finishing Products or ML Campbell's AC Sealer (eight hour pot life, catalyzed 10% with their catalyst, and must be sanded within a day or it hardens up too much to give an efficient sanding). Using your topcoat to fill pores tends to invite shrinkage down the road, so you go back almost to square one with a textured, semi-filled, porous film.

From the original questioner:
I knew I would have to sand back a good ways, but didn't realize I would have to go so far back. This brings up another point. I used the precat because that is what I have on hand and use on my cabs. What is a more appropriate finish for furniture? My precat cures too fast and even with a retarder, I battle over spray on the legs and such.

From contributor B:
Some of your finer furniture companies still use nitro lacquer.

From contributor F:
There is nothing wrong with using pre cat for furniture as long as you are not trying to do a high build finish with it. If you keep the dry film thickness to a four mil maximum you can use pre cat without worry. However I would not use it on a table top or other surface that will see heavier wear and moisture. In that case I would use at least post cat conversion varnish or in the case of a high build finish a 2k urethane as I previously mentioned.

Furniture re finishers tend to like good old straight nitrocellulose lacquer because it's cheap, easily reversible, rubs and buffs beautifully and does not have the mil thickness limitations of catalyzed products. But again, I would not use Nitro for table top either. As to the problem with how fast it is drying: check with your supplier to make sure you are using the right retarder for the finish, they are not all the same.

From contributor D:
Nitrocellulose lacquer is a furniture grade finish because it lends itself well to multi-step finish schedules, some with as many as more than 25 steps/operations. You can layer on color step after color step.

Cabinet grade coatings which are more durable and also conversion coatings (going from air-dry to reactive and crosslinking as the coatings set up) do not lend themselves to that many different coloring steps that traditional lacquer does.

The user of a cabinet grade coatings is much more concerned with creating intercoat adhesion problems because of the limitations of these coatings. When too much time has gone by then you have a coating that does not burn into the layer underneath to form one continuous film. Lacquer forms one continuous film, one coating burning into the previous. The rich look of furniture these days is nicely approximated with many cabinet grade coatings. You can do multi-step finishing with cabinet grade coatings, just not as many steps.

Suites of furniture have to match, one cutting to the next. Creating schedules that are faithful in their looks cutting after cutting is part of all those many finishing and coloring steps in furniture. This is not the case in cabinetry and office furniture where there's a lot more custom matching, one-offs, and tolerances for variations. Office furniture tends to be monochromatic, little to no highlighting the cathedrals in the woodgrain, little to no strikeoffs or glaze, and so on.

Retail furniture is a whole different ball game in the eye of a customer than is cabinetry. It's not just the cost of the lacquer. It's the need to create a lure for the customer. It's proven marketing with a track record that is many decades old. This is the way Americans shop for furniture and that's not going to change.

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