Dewaxed shellac vs lacquer sanding sealer before precat lac

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redknife

Chris
Corporate Member
I have two projects with the following planned schedule: Transtint dye (water diluent), Zinnser dewaxed shellac, Mowhawk precatalyzed lacquer. All sprayed.
I want to use the dewaxed shellac to seal the water soluble dye so that it doesn't get solubilized by the pre-cat lacquer.
The Mohawk instructions for the pre-cat recommend their sanding sealer which I believe is dilute lacquer with additives. I've seen references elsewhere recommending vinyl sanding sealer before pre-cat lacquer.


I'd like to use the dewaxed shellac because I use it for other things whereas a dedicated lacquer sealer is a less common need.

Has anyone applied water based pre-cat over dewaxed shellac or know this is OK?

(other options- trial run, call manufacturer which would have to wait till next week)
 

danmart77

Dan
Corporate Member
I have two projects with the following planned schedule: Transtint dye (water diluent), Zinnser dewaxed shellac, Mowhawk precatalyzed lacquer. All sprayed.
I want to use the dewaxed shellac to seal the water soluble dye so that it doesn't get solubilized by the pre-cat lacquer.
The Mohawk instructions for the pre-cat recommend their sanding sealer which I believe is dilute lacquer with additives. I've seen references elsewhere recommending vinyl sanding sealer before pre-cat lacquer.


I'd like to use the dewaxed shellac because I use it for other things whereas a dedicated lacquer sealer is a less common need.

Has anyone applied water based pre-cat over dewaxed shellac or know this is OK?

(other options- trial run, call manufacturer which would have to wait till next week)
Most everything will adhere to shellac used as a sealer. If I were you, I'd do what has been said on this site over 100 times: do a test piece to be certain. There's no substitute for the confidence you will gain be seeing the finish schedule start to finish.

Dan
 

Willemjm

Willem
Corporate Member
I have not used Mohawk products, so I cannot vouch for their sanding sealer. I can however assure you that you will be better off using Mohawks's recommendation and use their sanding sealer. Although I can get a perfect finish using dewaxed Shellac, it takes me 5 times as long and normally follows with a number of cuss words. ;-) You may want to include a retarder with Mohawk to make sure the finish sets up properly right out of the gun with no further work required. This is something I would do if I have not used the manufacturers finish before.

Using a normal lacquer sanding sealer with Transtint is extremely easy and forgiving compared to Shellac. The sanding of the seal coat takes seconds, compared to Shellac.

Every time I work with Shellac I use a fraction of what I bought and then either give or throw the rest away. Then I try and figure out why I have to learn the lesson over and over. I can't help but think Shellac is just for the old timers who have not yet discovered finishes that gives you a perfect professional finish with no hassles right out of the gun. Sanding only the seal coat in seconds, no further sanding between coats needed.
 

golfdad

Co-director of Outreach
Dirk
Corporate Member
Red have you thought about using Mohawk's Water Based Lacquer. Im on my second project with it. Sprayed it over a waterbased stain and used it as the sanding sealer. Excellent results...fast drying...easy cleanup
 

redknife

Chris
Corporate Member
Dirk, I'll do some test runs like Dan suggested and see how it looks with Transtint and the lacquer without sealer. It is one of the mfg options. I've been reading about the dyes and it is often suggested that dewaxed shellac be applied so the Transtint doesn't resolubilize but that may not be an issue with this product. If it doesn't come out as intended, I'll go with the Mohawk sealer and see if that works better.
 

danmart77

Dan
Corporate Member
Every time I work with Shellac I use a fraction of what I bought and then either give or throw the rest away. Then I try and figure out why I have to learn the lesson over and over. I can't help but think Shellac is just for the old timers who have not yet discovered finishes that gives you a perfect professional finish with no hassles right out of the gun. Sanding only the seal coat in seconds, no further sanding between coats needed.



Willem
If you think you might continue to use shellac for other applications, it sounds like its time to learn a simple lesson: Do Not use shellac from a can. Use flakes and mix fresh shellac for each project. The shellac will be a better quality and you will use what you need and store the flakes for a long time if you keep them dry.

The Bulls-Eye(zinseer) shellac from a can has never come close to performing like mixed shellac with pure ingredients in the 30 years I have been using it. Its just never performed equally for me and like you said it just sits and goes bad after 6 months.

just a thought
 

Jeff

Jeff
Corporate Member
I want to use the dewaxed shellac to seal the water soluble dye so that it doesn't get solubilized by the pre-cat lacquer.
I have no dog in the fight but here's a few thoughts to snarl and yelp about...

1. TransTint dyes are also soluble in alcohols, i.e., ethanol/shellac, lacquer thinners.

2. Try the simplest combination on some scrap and see how it does.
 

redknife

Chris
Corporate Member
I have no dog in the fight but here's a few thoughts to snarl and yelp about...

1. TransTint dyes are also soluble in alcohols, i.e., ethanol/shellac, lacquer thinners.

2. Try the simplest combination on some scrap and see how it does.
Will be doing #2. Most of us work alone in the shop and sometimes it helps to have others with experience in an area keep you on track. For instance, Dan emphasizing that testing is always the way to go. As to #1, I think the notion (based on reading, not experience) is that the dye may temporarily solubilize in the dewaxed shellac but not the topcoat once sealed. Some contend that when the dye solubilize in the topcoat it has a less desirable or different look. You may be right and it may be no different. No shortage of opinions about finishing. Thanks to all that responsed.
 
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