Lacquer Finish and problem Cherry

[Blaughn]

I have hit a run of finishing problems that threatens to ruin several plaques. 

Years ago a relative gave me a 36"x4"x4" piece of Cherry.  I estimate this to be 40 years of air drying and it had a crack that I had to work around.  Going from this stock to a plaque that was ready for its final finished involved a lot of work as only we scrollers can appreciate.  Upon finishing I discovered this cherry had areas that absorbed lacquer like a sponge. In short I was never able to get a coat of lacquer across the entire surface.  Here's a sample to show the issue:

The picture shows 2 scrap pieces of this cherry which are "book cut" to provide identical surfaces for finishing.  You can see the piece on the right with 4 heavy flow-coats of lacquer has a sizeable area where the lacquer has been fully absorbed.  The piece on the left had 1 coat of sanding sealer shellac  and 3 coats of lacquer.  The difference shown in the picture doesn't do justice to the actual difference.  I could do a light surface sand the piece on the left and apply the final coat of lacquer and it would be ready for the final hand rubbed finish.  The piece on the right would take many more coats of lacquer which might defeat the spongy areas.  Only a scroller can appreciate the frustration this causes.

The sanding sealer shellac (a wax free shellac) eliminated the absorption issue.  I applied a coat of sanding sealer shellac (which dries in 30 minutes) to the plaques I thought were ruined and then applied lacquer.  I think I can salvage them.  Going forward this will be my finishing routine.  The shellac works equally well over properly dried "danish oil" as a sealer as well as on bare wood before the final finish.

I love scrolling.  I don't love finishing.  Hopefully this will help others who are similarly challenged.

Edited July 17, 2022 by Blaughn

[Dan]

SealCoat is a great product. I use it to seal MDF before I paint. I have also used it on hardwoods to get a faster final coat. 

[WayneMahler]

I have also used shellac for woods that get really blotchy when applying stain. Pine, Poplar Sheet goods. That stuff can save your bacon in a lot of different ways.

[Davevand]

I have used this procedure for a long time. The only issue I have had is I need to be patient, let the shellac fully cure, not just dry before you put a top coat of lacquer on. If you are going to do a final hand rubbed finish you will need to let the piece sit and fully dry for at least a couple of weeks before you start. I have had to refinish some pieces that I have left finger prints in just moving them around the next day.

[OCtoolguy]

On this subject, I'd ask this question. Those of you who do a lot of projects in BB ply, how to you finish them? I made some tissue box covers and had a terrible time to stain to the desired color. I've backed away from staining BB and will either leave it natural with just a clear coat or paint it after using a sanding sealer. I admit that I'm very ignorant re: finishing so any help is appreciated. So far my finishing has been retricted to soaking in Watco natural and then after a good drying period, a couple coates of Zinnser's spray shellac. I'd love to know how to truly achieve a fine finish.

Edited July 17, 2022 by OCtoolguy

[Badgerboy]

5 hours ago, OCtoolguy said:

On this subject, I'd ask this question. Those of you who do a lot of projects in BB ply, how to you finish them? I made some tissue box covers and had a terrible time to stain to the desired color. I've backed away from staining BB and will either leave it natural with just a clear coat or paint it after using a sanding sealer. I admit that I'm very ignorant re: finishing so any help is appreciated. So far my finishing has been retricted to soaking in Watco natural and then after a good drying period, a couple coates of Zinnser's spray shellac. I'd love to know how to truly achieve a fine finish.

Ray, when I am staining BB, I always apply a coat of WAX FREE or dewaxed shellac then lightly sand with 320 after it is completely dry, tack cloth then stain. It is important to use dewaxed shellac as waxed shellac does not play nice with water based or solvent based final finishes. The amount of sanding you do can be played with is you want a less consistent stain job, play with it and you will figure it out quickly.  

[OCtoolguy]

15 minutes ago, Badgerboy said:

Ray, when I am staining BB, I always apply a coat of WAX FREE or dewaxed shellac then lightly sand with 320 after it is completely dry, tack cloth then stain. It is important to use dewaxed shellac as waxed shellac does not play nice with water based or solvent based final finishes. The amount of sanding you do can be played with is you want a less consistent stain job, play with it and you will figure it out quickly.  

The only shellac I've used to this date is the Zinnser's spray. Should there be something regarding wax on the can? I'll check it out but is it that easy?

Another question comes to mind. These boxes are BB inner and outer. I want to leave the inner box natural but with some sort of finish applied to it just to seal it off. Then the outer BB is where the pattern is cut. This is the part that will be either stained or painted. In this case, it will be stained so you've answered that question. What can I use to seal the inner box but still be able to attach the outer panels with Weldwood glue?

 

 

Edited July 18, 2022 by OCtoolguy

[Badgerboy]

Just now, OCtoolguy said:

The only shellac I've used to this date is the Zinnser's spray. Should there be something regarding wax on the can? I'll check it out but is it that easy?

 

Yes, as in the picture above dewaxed shellac will be labeled as such or just look at the contents. Here is an example, these two signs are cut from the same sheet of BB ply, both have the same shellac.  I sanded the darker one more and let the stain sit 30 seconds longer otherwise everything else is the same. Grain pops but is not splotchy. 

[Tom-in-Ashland]

I found when I was making custom furniture that Zinsser will impart a little yellow/amber tint to the wood which gets worse with the more coats used.  Suggest you consider buying Plantina or Supper Blond flakes and dissolving  it in denatured alcohol yourself.  A good source for shellac flakes is https://www.shellacshack.com/colors.html

[John B]

I find this strange, that shellac will seal the timber but lacquer wont.
I was taught that "Sanding Sealer" really just takes the place of coat number 1, but in the case of gloss finishes, it will cut back easier. I have never used it and neither have any of the polishers I have worked with.
The only explanation that I can think of regarding the lacquer soaking in and requiring so many coats, is that it was thinned to much.
Glad you found a solution to the problem.

[Blaughn]

22 hours ago, Davevand said:

I have used this procedure for a long time. The only issue I have had is I need to be patient, let the shellac fully cure, not just dry before you put a top coat of lacquer on. If you are going to do a final hand rubbed finish you will need to let the piece sit and fully dry for at least a couple of weeks before you start. I have had to refinish some pieces that I have left finger prints in just moving them around the next day.

Hi Dave:

I have heard that advice for Watco Danish oil or other oil-based finishes.  I have searched the archives of Fine Woodworking Magazine and the web site Lumberjocks.  The longest cure time recommended there for Seal Coat (unwaxed) shellac is 1 to 4 hours depending on humidity (high humidity takes longer).

Bruce

[Blaughn]

On 7/18/2022 at 3:16 AM, John B said:

I find this strange, that shellac will seal the timber but lacquer wont.
I was taught that "Sanding Sealer" really just takes the place of coat number 1, but in the case of gloss finishes, it will cut back easier. I have never used it and neither have any of the polishers I have worked with.
The only explanation that I can think of regarding the lacquer soaking in and requiring so many coats, is that it was thinned to much.
Glad you found a solution to the problem.

I think you may have put your finger on the problem.  Spray lacquer is thinned (25% or more) to permit spraying.  It could be that the spongy areas of the wood have a grain structure that prevents the thinned lacquer from "bridging across the cells".  The shellac based sanding sealer goes on with a relatively thicker coat and since shellac is dissolved in alcohol the lacquer thinner does not disturb the seal coat.  I will have to do some additional searching to test this guess.  In any event, for me, a shellac seal is saving a lot of time and effort.  For hang-on-the-wall plaques its durability should be more than adequate.

[barb.j.enders]

On 7/17/2022 at 9:39 PM, Tom-in-Ashland said:

A good source for shellac flakes is https://www.shellacshack.com/colors.html

My husband was putting together a guitar kit and purchased shellac flakes from here.https://www.woodessence.com/Shellac/Dry-Shellac  Now that he has finished the guitar, I "stole" the shellac.  Dissolved the flakes in 99% Isopropyl alcohol.  Just trying it out on a project now.

[Blaughn]

21 minutes ago, barb.j.enders said:

My husband was putting together a guitar kit and purchased shellac flakes from here.https://www.woodessence.com/Shellac/Dry-Shellac  Now that he has finished the guitar, I "stole" the shellac.  Dissolved the flakes in 99% Isopropyl alcohol.  Just trying it out on a project now.

Let us know how that works for you.  I have read that the best shellac solvent is Everclear alcohol (95% pure grain alcohol aka 190 proof).  This is not sold in Minnesota.  A "close at hand" diversion if your project doesn't work out okay!  

[Davevand]

On 7/18/2022 at 10:41 AM, Blaughn said:

Hi Dave:

I have heard that advice for Watco Danish oil or other oil-based finishes.  I have searched the archives of Fine Woodworking Magazine and the web site Lumberjocks.  The longest cure time recommended there for Seal Coat (unwaxed) shellac is 1 to 4 hours depending on humidity (high humidity takes longer).

Bruce

I am not sure when I read an article on this type of finish, probably late 90 or early 2000's. The author stated that he would wait at least over night, longer if possible between the last coat shellac and the first coat of lacquer, he then would wait at least a week before he would do any kind of buffing or waxing.  He also stated that he would always use gloss lacquer to build up the coats then use semi-gloss or satin for the last one or two coats.  This would give you the sheen you want without a "muddy" (as he called it) look to the finish.

[barb.j.enders]

21 hours ago, Blaughn said:

Let us know how that works for you.  I have read that the best shellac solvent is Everclear alcohol (95% pure grain alcohol aka 190 proof).  This is not sold in Minnesota.  A "close at hand" diversion if your project doesn't work out okay!  

Here is his guitar with the shellac finish.  He is quite proud of it.  Everclear, if available, would be way too expensive to use for this.  The isopropyl alcohol is what the guys at Woodessence  recommended.

[John B]

I use Methylated spirits (Metho). I think it is roughly the same as your isopropyl alcohol.
It has been altered slightly over the years. Now it has some additive that tastes really bad, so they say, to stop the drunks from drinking it and it has a purple colour added, but it does not effect it's use..

[BadBob]

I use denatured alcohol.

[barb.j.enders]

1 hour ago, BadBob said:

I use denatured alcohol.

Couldn't find denatured alcohol.  The isopropyl is what the supplier recommended.  Seems to have worked out well.  I was able to buy a 4 pack at Costco pharmacy so it was relatively inexpensive.