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There's a bunch of anecdotal evidence on this forum and elsewhere that KTM-SV doesn't adhere well to shellac - dewaxed or otherwise.

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Cheers
Pete

I know, some of it from me.
My dewaxed shellac was all Zinsser spray can stuff. I haven't yet had the chance to try it with homemade flake shellac, which I now have.
Other people with a great deal more experience and knowledge than me have used it successfully. I will say that I have had problems with oily woods, but that comes, apparently, as a result of sealer issues. I will also say that none of the guitars that I've used it on have displayed any problematic symptoms of any sort.
I'm sure with a little practice the right fill/sealer combo can be found.
Don't let my limited troubles turn you off of trying what I believe to be a really good non flammable topcoat.
I know I will be using it again when I can mess around with it more.

I got an email from Greven. Epoxy pore/wash coat and Target EM 6000.

That's surprising to me. That makes (at least) 3 well know builders, all of which have my respect who use waterbornes. As I said earlier waterbornes are still basically in their infancy. I'm not ready yet.





Zinsser shellac has a flammability rating of "3", same a nitrocellouse lacquer. Nitro has a lower flash point though, but the flash point of zinsser shellac is still low at 63 degrees F. I can't grasp the concept of a "non flammable top coat" if you're going to use a flammable sealer.

FWIW, alot of polyurethanes advise against applying over shellac. I think wax may actually be the problem, instead of the shellac itself. Zinsser spray shellac says "wax free" on the can, but the same product in non aresol form says it contains wax. I believe Zinnser seal coat would be a better choice for a shellac sealer. (No experience to back that statement up though)

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Another vote for EM6000. I started the waterborne journey with KTM 9 about 5 years ago. First by just wiping on (too thick, difficult to control), switched to thinned about 50% with denatured alcohol with a cheap HVLP gun. That improved the result..But...3 years ago I switched to Target coatings. First EM2000, then its successor-EM6000. I spray straight from the can (filtered but not thinned) HVLP gun. System 3 Clear coat epoxy filler and/or wash coat first. Pops the grain very well.
I have had zero issues with wear, sweat-induced breakdown and regularly get compliments on the quality of my finishes. I would un-reservedly recommend EM6000.
I plan to try the Target conversion varnish one of these days to see what that may offer, but in the meantime EM6000 is my finish of choice.

Woody, what do you think it will take to change your opinion that waterbornes are in their infancy? You may be correct of course, but given that - as you point out - some well-respected builders have embraced them wholeheartedly, I think it's a valid question.

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Cheers
Pete

I'm curious if anyone who did have chemical erosion issues with kTM-9 does not have it with EM 6000...
Reviewing my notes, I did try the sealcoat with a preval sprayer as well as the aerosol stuff. With the fan off but the window open, walled off from the furnace. Seemed safe enough. But I wouldn't want to pile on a whole bunch of volatile topcoats like that...

It is a valid question. One thing it will take for me, is a bunch of 10 + year old guitars. Waterborne finishes consist of a bunch of stuff that doesn't mix, all mixed together. That's why they're milky colored.
One of my biggest concerns, and one of the main reasons I try to point out alternatives to waterbornes is the assumption that waterbornes are "safe". They aren't flammable, but the don't need to be inhaled.

Meddlingfool, I've got a safe spray booth, with an explosion proof fan ect, but it sounds to me like you took more precautions when spraying shellac that I usually do. Good job. I've probably sprayed shellac inside shop (not my booth) while someone was smoking. LOL What still baffles me is reading about someone using waterbornes because of VOC's or flammability, then cleaning their gun with acetone, lacquer thinner, and /or alcohol. I protect my lungs, eyes ect, but probably don't pay as much attention to the envoriment as I should, and I probably (except for what happens inside my booth) don't pay as much attention to fire and explosions as I should.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

John Greven has been spraying waterbornes for at least 10 years, of one variety or another. His process varies only slightly with the product. He and Doolin really worked this thing out. That Doolin, Greven, Sheppard, me and several others have used the waterbornes successfully should be a fair indicator of the robustness of the technology -- it should be a fairly large sample size that if there was really a problem, we'd know about it. Most of the changes from product to product happened because either a better product came along, and/or a previous product was changed not to our liking. John makes something like 25-30 guitars a year, that's 300 instruments finished with waterbornes in the last decade. What's the likelihood that in that sample alone, ignoring that Doolin is a gigging musician and has caustic sweat and bench tested these finishes for this kind of durability, that none of the owners of those 300 guitars had caustic sweat. Possible, but unlikely. I think the technology is proven. I got away from it because at the time, the product I was using was prone to air bubbles and I didn't have time to mess around. I haven't looked back. It's not that the waterbornes don't have similar finishing schedules to other finishes in terms of curing, but if I have a problem with the catalyzed finish I just respray and a few days later I'm back in business. The waterbornes take longer to cure. I once said, "Friends don't let friends spray waterbornes," but this was unfair. Look at Gerald Sheppards guitars and tell me that isn't a perfectly downtown finish worthy of the work on which it is sprayed?

Dave makes a really good point. I have been spraying Target Coating's w/b lacquer for over three years, started out with USL and am now using EM6000. Having cut my teeth on nitro years ago, w/b lacquer is not as user friendly with regard to application. Care has to be taken to not contaminate the surface, humidity and temperature cannot be at extremes, high quality air is a must, and the gun setup is important. But once the finish is down, it is easily leveled and buffed to a gorgeous shine, and it holds up extremely well--I have yet to see any lacquer peel off or go soft under sweat.

Yeah EM6000 can be a little quirky to lay down, but it is a seriously good finish.

I have used Target's pore fill under EM6000 but am not a fan. For the last two guitars I used zpoxy with a wash coat, which is now my preferred approach.

Ken

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http://www.casperguitar.com

Woody - can you help me understand this statement? My VERY limited understanding of waterborne lacquer (eg EM6000) is that tiny particles of resin are suspended in a solution of water and solvents. When applied, the water evaporates first, concentrating the solvents and allowing them to "dissolve" the resin particles long enough to cross-link(?) before the solvents evaporate. Is that accurate? If so, how would the cured finish differ from a standard nitro lacquer finish?

I haven't actually looked at these finishes under a microscope, but it's my understanding that evaporative finishes (like nitro) consist of long skinny molecules that are disolved in solvent. When the solvent evaporates the molecules kinda become entangled. Re introducing the solvent will disolve them again.

Varnishes, Urethanes, Polyester, ect, "reactive" finishes consist of round molecules. When exposed to a catalyst (oxygen for varnish) a chemical reaction causes the molecules to attach to each other, or cross link.

Waterborne finishes consist of ground up molecules of finish that are already cross linked. In my mind, it like ground up finish, contained inside little bags. These little bags of finish are suspended in a mixture of water, and solvent, (usually glycol ether(?)). When the water evaporates the solvent partually melts the little bags containing the finish and sticks it together. If everything works correctly I suppose it is similar to an evaporative finish, like Nitro. I'm not really much of a Nitro fan.

Blanket statements are........................tough, but for the most part I prefer reactive finishes over both evaporative, or coalesceing finishes.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Em 6000 does a good job for me .Easy for small shop use.I shoot a couple of coats of shellac.DE-Waxed that I mix myself.About a pound and a half cut.Pore fill with Ca .Then a couple of more coats of shellac.Then shoot the 6000.Used to use Nitro,and I loved the stuff,the wife didn`t.
James

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James W Bolan
Nashville Tennessee

First of all that would be one heck of a microscope. Even electron microscopes can't see individual molecules although they can now see nano materials with recent developments.

Nitro is not "long and skinny: and urethanes are not round. In fact, nitrocellulose monomers are more "round" than urethane monomers, but that doesn't really matter at all. They both form long chain polymers. These polymers, nitrocellose, polyurethane, etc., do become intertwined but more importantly they form bonds known as Van der Waal forces. These are much weaker than the covalent bonds that result from crosslinking, but are very important in all finishes. Even reactive solvent based varnishes don't form one giant polymeric molecule over the surface as a result of crosslinking, but are composed of an indescribable number of individual polymeric molecules, think Avogadro's number.

The difference between evaporative finishes, coalescent finishes (waterbornes) and reactive finishes is not black and white, but more of matter of degrees. Evaporative finishes like nitrocellulose are relative short uncrosslinked polymers. Because of this they readily redissolve. Reactive finishes are relatively long chain, highly cross-linked polymers that don't redissolve. Waterbornes are not made by grinding up preformed polymers, but by either forming the polymers in water or by forming them in solvent and then adding water. They are not as highly crosslinked as reactive finishes, but are a lot like them. Again both waterbornes and reactive finishes are composed of many individual polymeric molecules. It's just that reactive finishes are more crosslinked, but it is a matter of degree. This is why a good waterborne does not readily redissolve. However, it does take waterbornes a lot longer to fully coalesce. This can be seen as an advantage over reactive finishes, since there is a good window to recoat and get burn in.

Also note that isocyanate is not the catalyst for the urethane barrier coat, but is the actual monomer for forming the urethane.

I use KTM-SV with great success. All the other waterbornes mentioned contain acrylic while KTM-SV does not. Every acrylic containing finish I have seen will show a blue cast on dark woods when viewed in direct sunlight. Also KTM-SV is harder, more chemically resistant and has a great hand feel. EM-6000 is easier to apply though.

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Randy Muth
RS Muth Guitars Website
RS Muth Guitars Blog
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Randy - I get the distinct impression you understand this stuff far better than I ever will.

Thanks for the excellent explanation!

In the "FWIW" category....

I've sprayed KTM-SV over Zinsser SealCoat with success on two non-guitar projects.

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

And while I'm no expert, I sprayed KTM-SV over Zinnser SealCoat on the soundboard of my last guitar with success. Also, I pore filled EIR using Zpoxy and left a very thin barrier coat of zpoxy to pop the grain and use as a barrier coat between the oily EIR and the KTM-SV. It also seems to have worked fine.

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Formerly known as Adaboy.......

Not to hi-jack the topic but...I think we can see pictures of molecules. Sort of depends on your definition of "see". Here are some examples of individual atoms (well, the electron clouds).

http://physicsbuzz.physicscentral.com/2009/09/first-detailed-photos-of-atoms.html

Pat

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There are three kinds of people:

Those that make things happen,
those that watch things happen,
and those that wondered what happened.

Pat, I stand corrected. Yet another recent development using the electron microscope. Of course this was a very specially prepared sample. When using a tool like this, the matrix is critical. Very cool though.

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Randy Muth
RS Muth Guitars Website
RS Muth Guitars Blog
Facebook Fan Page

Anybody having success using KTM-SV over regular shellac??

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Dave
Milton, ON