# Can I apply polyurethane finish over a lacquer finish if I use Zinsser sanding sealer



## MNsawyergp (Jan 31, 2012)

I have stripped, stained, and sprayed on 2 coats of Gemini pre-cat lacquer to a walnut dining set and buffet. I am wondering if putting coats of polyurethane finish on the table top will add any durability. Please give any experience you have had. I am wondering if applying Zinsser sanding sealer will seal off the lacqeur so it won't affect the polyurethane. Has anybody done this? Is it worth doing?


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## Steve Neul (Sep 2, 2011)

Since you have started with lacquer, I would continue with lacquer. The pre-cat lacquer is a pretty good finish for furniture and you won't get as good of a bond to the lacquer with the Zinsser Sanding Sealer. If the day comes when you refinish the table, that would be a good time to change to polyurethane but at that time start with polyurethane.


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## MNsawyergp (Jan 31, 2012)

Thanks for your wisdom. I normally use laqcuer for any cabinets I make. I don't really like using Polyurethane. It is messy, sticky, and doesn't sand out to a final finish like lacquer does. Can you tell if there really is that much difference in hardness after they are cured?


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## Steve Neul (Sep 2, 2011)

Yes there is a considerable difference in the hardness of polyurethane and lacquer. Polyurethane is harder and more water resistant. Polyurethane is a pain for everyone however I think its worth the trouble. They make waterborne polyurethane that dries quicker but since it has water in it, it raises the grain and creates a lot of sanding between coats and more coats then the solvent counterpart. I can normally finish with oil based poly in two coats. I normally spray what I'm working on late in the afternoon just before quitting time and the next afternoon sand the first coat and put the final coat on. I don't have very good working conditions anymore so I normally spray the piece and leave the building for the day.

The reason I got cold feet about using the sealcoat over lacquer is lacquer works by using the strong solvents to melt into each successive coat that is applied. Lacquer actually finishes as one thick coat instead of layers. I don't believe the solvents in sealcoat are strong enough to get a bite into lacquer so you would be ending up with a separate layer over the top that I believe would peal taking the poly with it. I haven't tried it so I'm going on instincts. I know if you continue with lacquer it would be up to industry standards for a table top finish. On a future project a harder lacquer you could use would be a fully catalyzed lacquer. It would go over the vinyl sealer just like your precat. I understand where you are coming from using lacquer. I love it myself but I have to think more on durability than being easy to work with.


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## MNsawyergp (Jan 31, 2012)

I understand what you are saying about the separation of layers, and that is what I was afraid of. Last year I had a customer who wanted their oak table top re-finished because the factory finish was peeling off in a couple spots and it had a cigarette burn in it. Silly me, I thought I could touch up the spots and put a coat of Zinsser sanding sealer on it, then add coats of polyurethane. Well, after several more spots of the old finish lifting off and touching them up, I finally got a smooth surface to add more layers to. I did finally get a beautiful finish on that table, but the time I spent and the whole process of waiting a day between coats was very aggravating. Even then, I was scared that some day the customer will slide something across the table and a layer will peel off.

This current project is a referral from that previous table top. It is an antique set handed down from the grandparents. I did a set like this back in 1987. I swore I never wanted to re-finish a fancy dining set ever again. Well, here I am. I am Mr. nice guy and couldn't say no. Now that I am disabled, because of my back, I am not worried about the time frame, so I told the customer that I would putz away at it until I got it done. That was fine with her, because she was in no hurry.

I guess my problem is that I am always a perfectionist and I put too much thought into what is the ultimate best product. I need to be satisfied with what I have done. Thanks for your input, Dr. Phil, now I can rest in peace, knowing I did my best. Hopefully, it will be another 25 years before I see another antique dining set.


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## Steve Neul (Sep 2, 2011)

MNsawyergp said:


> I understand what you are saying about the separation of layers, and that is what I was afraid of. Last year I had a customer who wanted their oak table top re-finished because the factory finish was peeling off in a couple spots and it had a cigarette burn in it. Silly me, I thought I could touch up the spots and put a coat of Zinsser sanding sealer on it, then add coats of polyurethane. Well, after several more spots of the old finish lifting off and touching them up, I finally got a smooth surface to add more layers to. I did finally get a beautiful finish on that table, but the time I spent and the whole process of waiting a day between coats was very aggravating. Even then, I was scared that some day the customer will slide something across the table and a layer will peel off.
> 
> This current project is a referral from that previous table top. It is an antique set handed down from the grandparents. I did a set like this back in 1987. I swore I never wanted to re-finish a fancy dining set ever again. Well, here I am. I am Mr. nice guy and couldn't say no. Now that I am disabled, because of my back, I am not worried about the time frame, so I told the customer that I would putz away at it until I got it done. That was fine with her, because she was in no hurry.
> 
> I guess my problem is that I am always a perfectionist and I put too much thought into what is the ultimate best product. I need to be satisfied with what I have done. Thanks for your input, Dr. Phil, now I can rest in peace, knowing I did my best. Hopefully, it will be another 25 years before I see another antique dining set.


When you work on antiques most of the time you can just touch up the finish with lacquer. Even if it has varnish on it, its so old, hard and dry you can get away with putting lacquer over it as long as you don't flood a wet coat on it. Of course you need to test in a inconspicuous place to be sure. I feel more comfortable recoating a piece with lacquer than polyurethane. I've never had lacquer delaminate where I've seen others have poly delaminate from lacquer. Then if the furniture was done in the 1920's through the 1950's chances are the factory finish was lacquer anyway. What I normally tell my customers is when I touch up and recoat a piece is the old finish is failing, I can touch it up and recoat it but if more spots fail it will take the work I did off with it and that the only way I can assure them the finish will be good for them is to take it down to the wood and refinish it. That leaves you in the clear if it doesn't work because its pot luck anyway. 

There’s nothing wrong with being a perfectionist. There are too many people around doing shoddy work to make a buck. This country really needs to bring back craftsmanship.


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## cabinetman (Jul 5, 2007)

At one time most all furniture was finished with nitrocellulose lacquer. It's a hard finish. There are different lacquers now, but I wouldn't apply any lacquer over any oil base varnish or polyurethane, no matter how old. There may be no immediate reaction, but the possibility exists that there will be.

Some of the cons in using oil base is the dry time and the debris that it can attract, and the smell. You could use a waterbase polyurethane, and there are many that are suitable for flooring, and would be suitable for a durable furniture finish. I use a lot of it and there is minimal grain raising that gets dressed with just in between sanding. It stays clear, dries very fast, and is an easy clean up. Not a big deal.









 







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## MNsawyergp (Jan 31, 2012)

The finish on this dining set was in really bad shape, plus there were lots of scratches and damage to the set. The customer also wanted to change the color...so the only choice was to strip it. All in all, I stand by my conviction that it is so much more fun to build a new project than to re-do an old one, whether it is furniture or remodeling an old house. I almost have panic attacks thinking about the amount of work needed in re-doing somebody else's old project. 

Thank you for your input. I am going to study up on the fully catylized lacquer, though. I have avoided it because I don't spray that often and I don't know how soon I will use up the leftovers.

As for waterbased poly, I did buy that in spray cans for the table I did last year. Minwax has a neat spray tip on their cans which sends the spray out in a fan, like a spray gun. It can even be turned vertical to horizontal. I really like that product.


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## MNsawyergp (Jan 31, 2012)

Steve,
I looked at your projects. Wow!!! Did you make all of those from scratch? I don't really know anything about your profession, so are you a master woodworker with lots of CNC machines and employees? Fill me in. Tell me what kind of spray equipment you use. 

I used to have a shop back in 1977-84. I shut down and moved to Wisconsin and got into finish carpentry and custom cabinetmaking on sight in new houses. I kept my Speedflo 60-1 Commander airless spray pump all these years. I bought in 1977. It still works like a charm. I had to re-fit it with a Graco gun. Now, I work out of my basement and garage, mostly on my own house projects. I have taken up stained glass. It is not as dusty as woodworking.

Now that I am almost done with this dining set I will have time to check in here more often and chat with fellow woodworkers. I really enjoy this site.


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## d_slat (Apr 10, 2012)

Steve Neul said:


> There’s nothing wrong with being a perfectionist. There are too many people around doing shoddy work to make a buck. This country really needs to bring back craftsmanship.


what he said. I've seen way too much crappy work done just to say it's done. Glad to see some people still think the way I do.


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## Steve Neul (Sep 2, 2011)

MNsawyergp said:


> Steve,
> I looked at your projects. Wow!!! Did you make all of those from scratch? I don't really know anything about your profession, so are you a master woodworker with lots of CNC machines and employees? Fill me in. Tell me what kind of spray equipment you use.
> 
> I used to have a shop back in 1977-84. I shut down and moved to Wisconsin and got into finish carpentry and custom cabinetmaking on sight in new houses. I kept my Speedflo 60-1 Commander airless spray pump all these years. I bought in 1977. It still works like a charm. I had to re-fit it with a Graco gun. Now, I work out of my basement and garage, mostly on my own house projects. I have taken up stained glass. It is not as dusty as woodworking.
> ...


Yes I built everything from scratch. Actually I've never seen a CNC machine other than pictures. I started off doing woodcarving on my own before I found someone that I could take classes from. I believe the second picture was of a cedar chest I built for my wife to be 4 or 5 years before I took classes. My wife found an ad in the paper someone giving classes so I took them for about two years in the mid 1970's. His name is Ludwig Kieninger and from what I understand he is still teaching classes. 
As far as employees I never had very many as I was doing a lot of work you couldn't really train someone to do. At one time I did run an assembly line refinishing tables in the building in the cover photo. There was an antique dealer with a 10'000 sq. ft. warehouse behind mine that was full of gateleg and drawleaf tables stacked two high that needed refinishing. The man would get a shipment of tables from Europe and customers would pick over them and buy the good ones and the ones with the finish coming off or had paint splattered all over them that wouldn't sell went to this warehouse. I had one person strip the furniture and another that did what sanding had to be done. Then I had an aid that would move the tables into the spray booth for me to spray and he did the sanding between coats. When I was away he took care of the finishing as well so there was just the four of us. At the time I wasn't doing much remodeling or cabinets. It was primarily antique repair and refinishing. 

As far as finishing equipment, if I was finishing formal furniture like walnut or mahogany, I just used a air compressor and a conventional sprayer. The assembly line refinishing I was doing I had a production tank with a 25' hose and a conventional sprayer to spray lacquer sanding sealer and another rig set up the same only with semi-gloss lacquer. The assembly line refinishing was never intended to be high quality. It was just done to make the tables sellable. The finish was as durable as lacquer gets however we didn't get too fussy sanding between coats. We paid more attention to the top then anything.


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## MNsawyergp (Jan 31, 2012)

Steve,

I go by the saying, "The more I know, the more I realize there is to know". In one glance I can see the detail and intricacy of your work. I am in deep admiration of you. Often I have dreamed of carving in 3-D, but never got the opportunity. Thank you so much for taking time to answer me so personally and for helping everybody here.


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## Steve Neul (Sep 2, 2011)

If you want to do woodcarving, its not rocket science. It takes more patience and determination than anything. It is becoming a lost art because most people today want to slap a project together quick and easy. Few people are willing to spend weeks chiseling out a design on their furniture that serves no purpose but ornamental. That table that has the human figures on the corners I worked on it off and on for three years. I would work on it until I got sick of it and moved on to other projects. At the time I hadn't began my business yet so I had more fee time. Its been many years since I've done any carving other then for business purposes. The last carving I did was that corner glass cabinet I built for a customer in 2010. 

If you think you might want to take it up there are several woodcarvers here other than me and places like Rockler and Woodcraft sell carving chisels. You don't need 100 of them, I had only four until I took woodcarving classes and the teacher had me order a set which he gave me a list of chisels to buy. He recommended and had me purchase Frank Mitermeyer chisels. Not sure of the spelling. I'm not overly impressed with them or it may be that one broke one time and went through my hand has me prejudice. Over the years I have only accumulated only about 30 chisels, some of which have special purposes that rarely get used. I really don't see much difference in chisels. The straight chisels I have, I just use standard carpenters chisels with plastic handles. The last ones I bought were Harbor Freight and they work just as good as any of them. Anyway if you are interested I can give you a starter list of chisels that should make most things.


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## MNsawyergp (Jan 31, 2012)

Carving is on my bucket list. I may start out with a tree stump just for fun. I watch the chainsaw carvers at the state fair and see how they can visualize in a few minutes how to create a shape out of a huge block. I have also watched ice sculptors work. My carving amounts to using chisels and a router to make animal wall pictures. Now that I have more time I will eventually try 3-D sculpting. 

There is a store in Minneapolis that started out with a man which sounded similar to the man you learned from. I met him and his son back in 1979. The son now runs the store and gives the carving classes. Here is their site...http://www.woodcarversstore.com/

You have inspired me to move sculpting to a higher spot on my list. I may have some sculpting questions for you later. Thanks again.


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## Steve Neul (Sep 2, 2011)

With my internet I am not able to open the link. It would help to take some classes if you had the opportunity. I could help you some however I don't know how I could put into words how to sharpen and maintain the chisels correctly. This is probably the hardest part.


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## HowardAcheson (Nov 25, 2011)

<<<< I don't believe the solvents in sealcoat are strong enough to get a bite into lacquer s

The solvent in Zinsser Seal Coat is denatured alcohol. Denatured alcohol is also the primary chemical in almost all lacquer thinners.

On another point, most poly varnishes are formulated to be soft and flexible. By being soft they resist scratches and abrasions much better that a truly hard finish like solvent lacquer or most waterborne finishes. Poly's softness also is a plus in that it can withstand dings without damage


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