Finishing Question

Re: Finishing Question

Bill Tindall, E.Tn.

I make my own stain and it has linseed oil in it at times. I spray Sherwin Williams Kemvar over it, after a couple days of cure, with no adhesion problems. Of course when in doubt, test. However I expect lacquer or conversion varnish will stick to any cured finish.

Re: Finishing Question

Curt Putnam

A coat of shellac should do the trick

Re: Finishing Question

David Yoho

I've used that same Danish oil process many times, except I use 600 paper. The end result is the same however.

The only issue to be aware of is dry versus cured. Oil finish take a long time to cure but can feel dry sooner. If it were me, I'd wait at least a week before top coating with anything and feel good about it. Maybe even longer. However, I've applied top coats over oil in the past without adhesion problems.

Re: Finishing Options

Mark Mandell - Gone Round In New Jersey

My "standard" finish is to use Waterlox sealer, followed by dewaxed shellac and then topped with waterborne, either General Enduro Gloss poly or Target Emtec lacquer. I do allow the the oil to sit for several days to open cure although there's enough oxy in the wood to complete the cure.

I've used the oil-slurry method as a grain filler, but prefer to do that with the clear coatings to get a brighter finish coating. I also prefer the Waterlox to "Danish" oil because the tung oil carrier doesn't darken over time like linseed or other seed oils.

Old saying: "Shellac sticks to everything and everything sticks to shellac." Dewaxed shellac as a tie-coat solves a multitude of adhesion issues, but it must be dewaxed to work under waterborne finishes.

Old saying

David Yoho

I always heard that to mean dewaxed shellac only. Regular shellac contains some wax that can negate that claim.

Good point

John in NM

I bought some button lac for the color and also found it to be better behaved than dewaxed so I use it a fair amount. I've not had problems with compatibility, but then I don't use water carried finishes. That is a good one to remember!

Re: Finishing Options

Bill Tindall, E.Tn.

lacquer is used over oil based stains routinely. The binder in these stains is a curing oil/varnish. There is no need for the extra step of shellac.

Re: Finishing Options

Henry (Raleigh NC)

Bill:

What if Mark is using a waterborne product top-coat like (all of?) Target's products? These products Mark mentioned as top coats are not lacquers in the Nitro-cellulose sense of lacquers, but I believe an all-acrylic product (but I am not certain about that).

I would guess that's why he uses the shellac 'tie' layer.

Henry

Agree

David Yoho

In Mark's case he is applying a water based product over an oil based product and I think dewaxed shellac is the proper way to tie two dissimilar finishes.

Re: Finishing Options

Bill Tindall, E.Tn.

I am addressing the original question which involves a drying oil over coated with solvent based precat lacquer. Waterborne finishing is another topic. Unclear why these products and problems have been brought into the discussion.

Why?

Mark Mandell - Gone Round In New Jersey

To give Thomas some "Options" as stated.

Is there something wrong with that, Bill?

Confusion

David Yoho

Ok. My confusion stems from your response....

lacquer is used over oil based stains routinely. The binder in these stains is a curing oil/varnish. There is no need for the extra step of shellac.

...was a response to Mark's reply. Got it.

Re: Finishing Question

Raj

I have sprayed gallons of catalyzed lacquers. It's always a good idea to use a sealer that comes from the same manufacturer, typically a sanding sealer although you can use the topcoat as the sealcoat when it is thinned down. While it is true that shellac is a universal sealer, it will not have the strength characteristics that a catalyzed sealer will. Since you are already going to the trouble of spraying a catalyzed lacquer, and this must be sprayed, use the sealer that will make the total finish its strongest.

What is a "Laquer" Today?

Don Stephan

How many different non-identical products today are called by the manufacturer a "lacquyer?" My understanding is that originally it was a product containing essentially nitrocellulose lacquer and lacquer thinner. Now there are lacquers, pre-catalyzed and post-catalyzed lacquers, and I think water borne lacquers. Is there conversational value today in referring to a product as a lacquer?

definition

Bill Tindall, E.Tn.

Lacquer is a finish where the film forming polymer is dissolved in a solvent. Nitrocellulose and butyrate lacquer are just two examples. In contrast, varnish is formulated from materials that polymerize to form the film forming finish after application. The water based finishes are correctly called latexes. Here the film forming polymer is suspended in a liquid that is largely water. Any of these classes of finish can be formulated to cross link the polymer after application to yield a more durable finish.

THank you!