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Sounds like a good plan, Darryl, with the proviso that the ZPoxy is thoroughly washed to rid it of any blush before the KTM-SV top coats are applied.

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Cheers
Pete

Will soap and water remove the blush or should something else be tried?

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Formerly known as Adaboy.......

Plain tap water will do the job, although I did note that Jeff Weiss on the Target Coatings forum recommends washing cured epoxy with denatured alcohol prior to applying top-coats. If you're planning on applying KTM-SV over epoxy which hasn't fully cured, there may be problems given that the amines are produced as the epoxy cures. Good luck, and let us know how it turns out.

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Cheers
Pete

1:1 water/alcohol is a good wash solution for waterborne. I keep a bottle around all the time for wiping after filling, scuff sanding etc.

Rolfe does not use rosewood much if at all. He did however notice the problem at least one time on some ebony on the headstock and/or edge of the fingerboard.

I recently switched to CA for pore filler and will be doing some of my own experiments. I'll keep you posted.

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Randy Muth
RS Muth Guitars Website
RS Muth Guitars Blog
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Okay, this got me to register and get involved although I don't have time for another forum. I've been using KTM-SV for quite a while now and have never had an adhesion problem. The only problems I've had is with something migrating from Macassar ebony into the SV and creating a strange effect that sometimes would just wipe off. At that time I was using Target shellac for a sealer, and I learned that in order to make shellac waterborne, it loses much of its barrier properties. So, I switched to Zinsser Sealcoat, and everything has been fine. I recently learned that the Zinsser shellac has properties that create adhesion problems, but that's only their shellac not their Sealcoat. Tom Bazzolo has been building rosewood guitars for some years now which he's finished with KTM-SV, and he's had no problems. But he also uses Sealcoat.

Hi Rolfe, now I don't have to put words in your mouth. Just so you know, I wasn't implying that you had adhesion problems. I also haven't had adhesion problems. I was referring to the situation you had with the ebony. This migration problem has happened to me as well, and it appears to me that the KTM-SV just doesn't fully cure and stays a bit soft when this happens.

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

Rolf, thanks for taking the time to weigh in on this topic. You've used this product as much as anyone I'm guessing so your expertise is valuable.

So if there are no issues applying KTM-SV over SealCoat, I'm wondering what caused Pete and MF's issue where the the SV apparently didn't have a good bond to the shellac that was covering their spruce tops? Pete/MF, maybe you could give more detail on the prep and finishing technique you used. Just trying to figure out what could be causing this.

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Formerly known as Adaboy.......

Sure...
Three coats zpoxy only scuffed and not sanded back to wood. Three to four coats of shellac, left overnight and scuffed lightly in the morning. Ten coats of SV day one, one coat per hour. (boring day) dried overnight then level sanded with 3m 30 mic, not being too fussy about perfection just getting it reasonable. Eight more coats the next day. Sand with 30 mic, wait ten days, then sand with 15mic and buff with Menzerna 16/18.
On the mahogany guitars I only sprayed ten coats but I got a lot of burnthroughs. I think 18 was too many.
Randy, how do you clear off the paint for your bridges? And how do you find it for ding resistance? Does it harden up over time?

Oh, and except for the cutaway horn example, which I consider operator error, I'm not sure I'd say there's an adhesion problem. In fact I quite enjoyed just being able to dig a chisel through to wood and peeling out the bridge area. I still have that cutaway and the repair blended seemlessly and the rest is holding up beautifully.

Darryl, my finish schedule was very similar to that of meddling's. Epoxy pore fill on back, sides and neck only, which I didn't sand back to the wood. Let it cure for a day then shot three coats of de-waxed white shellac thinned to a two-pound cut and applied an hour apart. Next day, scuffed the shellac with a grey scotchbrite pad (the fine one), and went through the top-coat routine as described by Randy Muth in an earlier thread, i.e. six coats per day over two days, except for the soundboard which received only four coats on day two. It was some weeks before I had the chance to remove the finish in readiness for gluing the bridge (I masked with frisket film by the way).

I tracked down a local supplier of an Ilva product similar to the one Randy uses, but I'm a little reluctant to revert to a solvent-based sealer when it was the safe, environmentally-friendly aspects of KTM-SV which appealed to me in the first place - it would seem to defeat the purpose to some extent. I'd much prefer to use the Zinsser SealCoat Rolfe recommends if I can find a source for it here in Australia. Rolfe very kindly tracked down an Australian distributor of Zinsser products for me and I'll shoot them off an email today.

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Cheers
Pete

Spraying every hour seems a little fast to me, but maybe it's OK. I wait 1 1/2-2 hours between coats, usually 1 1/2 hours. Eighteen coats is a lot. I'm looking for 4 mills after sanding and buffing on my top and about 5 mills on everything else. If you got burn through with 10 coats, it's probably due to uneven spraying or sanding technique. Though it is my experience that spraying error accounts for most burn throughs. I level sand with 500 grit after the first 6 coats and never burn through. Never say never.

When I remove the finish for gluing bridges, I usually rout it off. I don't remove any wood when I do this. I have glued bridges directly to the finish, like Rick Turner does with polyester, and all are holding. I tried to rip one off and most of the soundboard came with it. A test piece of course.

Ding resistance. Well, when you ding nitro, the nitro cracks or chips. When you ding a varnish, the wood gets dented if it is soft, such as the soundboard. Polyester is pretty much like armor. This stuff is like varnish. It's a pretty hard varnish though. Most dings can be handled with very light sanding, often with 2000 grit, and then buffing out.

One more thing. Grafted Coatings calls this a spar varnish. Spar varnishes are generally soft long oil varnishes. This stuff is not at all soft like a spar varnish. It's too bad, because their terminology has probably scared some people away.

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Randy Muth
RS Muth Guitars Website
RS Muth Guitars Blog
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I could certainly believe inconsistant spray technique contributed to my burning through.
As for hardness, I can easily press a thumbnail dent into a guitar sprayed eight months ago. When I peel the bridge area it is completely flexible, you can twist it roll it into little balls etc. without it snapping.
Randy, next time you fit a bridge could you maybe try chiseling a bit out just to see what happens?

Hi Randy---yes, it was a strange problem that neither I nor Matt at Grafted Coatings could figure out, some sort of migration from the wood into the SV. As far as spraying goes, I would hesitate to shoot more than six coats in a day. Yes, it does cure in an hour, but the cure is not total, and there will be shrinking for a week. So, I shoot five, wait a day, level sand with 800, then shoot another two. I notice Tom Bazzolo doesn't shoot a lot of coats in a day. I've copied his schedule, and here it is:

Day 1:

 Finish sand wood surface to 3M 216u 400 grit
 Vacuum surface and tack wipe clean, wipe with naphtha
 Apply with a credit card first coat of Z-Poxy
Day 2:
 After overnight cure sand lightly with 3M 216u 240 grit, tack wipe clean and apply second coat
Day 3:
 After overnight cure sand lightly 3M 216u 400 grit, tack wipe clean and apply third coat, if necessary.
Day 4:
 After overnight cure sand lightly 3M 216u 400 grit, then wipe entire guitar with Z-Poxy applied with wet pad
Day 5:
 Sand level with 3M 216u 400 grit
 Vacuum and wipe clean with damp cloth
 Brush or wipe two coats Zinsser Seal-Coat Universal Sanding Sealer, one hours between coats
Day 6:
 Sand level with 3M 216u 400 grit
 Six coats KTM-SV Varnish, one hour between coats
Day 7:
 Sand level with 3M 366L 30 Micron grit on 3M rubber hand block
 Sand level with 3M 216u 800 grit
 Sand consistent scratch coat with grey Mirka
 Wet all edges and outside curves with alcohol soaked patch and Q-tip.
 Two coats KTM-SV Varnish, one hour between coats
Wait two days:
 Sand level with 3M 366L 15 Micron grit on 3M rubber hand block
 Final sanding with Abralon 2000 then 4000 all by hand
Wait 7-10 days:
 Buff with medium compound wheel across then along the grain
 Buff with fine compound wheel across then along the grain
 Buff with extra fine wheel along the grain

OK Rolfe, you got me to join a forum, something that I have never done. First, let me state that I am very pleased with application and results of KTM-SV; I use it on mt steel string guitars. Further, the good results I get using this finish came with the help of both Rolfe and Randy Muth.

This finish will not tolerate any contamination from oily tropical woods. You won't even know that the finish has failed until the time that you try to buff. What you will see is that the finish remains softs where it is in contact with a section of dark, oily grain. The surface will "depress" along those streaks. Although dry, the finish will never cure.

I have had finish failure using KTM-SV on ebony, Indian and especially Brazilian rosewood with all waterborne shellacs, Sealcoat and freshly made shellac. The only sealer I have used with 100% success is ILVA TF-25 Univeral Polyurethane Barrier Coat. Thanks Randy.

Here is my finish schedule as adapted from Randy's post on this forum.

Day 1:
 Finish sand wood surface to 3M 216u 400 grit.
 Vacuum surface and tack wipe clean, wipe with naphtha.
 Apply with a 6” plastic spreader first coat of Z-Poxy thickened with colloidal silica to rosewood.
Day 2:
 After overnight cure sand lightly with 3M 216u 240 grit, then maroon Scotchbrite. Tack wipe clean and apply second coat of Z-Poxy thickened with colloidal silica.
Day 3:
 After overnight cure sand lightly with 3M 216u 240 grit, then maroon Scotchbrite. Tack wipe clean and, if required, apply third coat of Z-Poxy thickened with colloidal silica.
Day 4:
 After overnight cure sand lightly 3M 216u 400 grit then maroon Scotchbrite. Vacuum surface and tack wipe clean, wipe with naphtha.
 With foam brush apply 3 coats ILVA Universal Polyurethane Barrier Coat two hours between coats. Sand lightly 3M 216u 400 grit then maroon Scotchbrite between coats.
 Spray 2 coats KTM-SV Varnish, two hours between coats.
Day 5:
 Drop fill if necessary.
 Sand level with 3M 366L 30 Micron grit or 3M 216u 800 grit. (If orange peel is heavy, use 3M 216u 400 grit lightly, then 3M 216u 800 grit.)
 Spray 2 coats KTM-SV Varnish, two hours between coats.
Wait 2 days:
 Sand orange peel level with 3M 366L 15 Micron grit, then 3M Microfine sanding sponge all on 3M rubber hand block.
 Final wet sanding with Abralon 2000 then 4000 all by hand.
Wait 7-10 days:
 Buff with medium compound wheel across then along the grain.
 Buff with fine compound wheel across then along the grain.
 Buff with extra fine wheel along the grain.


I hope this helps.

Thanks to everyone for this invaluable information.

Unless I'm misreading or misinterpreting what's been posted here and elsewhere, there does seem to be a discrepancy in terms of the number of top coats you're all prescribing. Can you all confirm the number of coats you're applying?

_________________
Cheers
Pete

Obviously, I haven't talked to Tom Bazzolo in a while; my bad. So, ignore the schedule I posted from his old handouts, and use his current experience as the new norm. I'll be updating the handout before the coming Symposium of ASIA next June. As someone noted earlier: I don't work with really oily tropicals; Macassar is my worst. This also makes a difference when it comes to how many coats I use. I don't use any filler and don't need to with the mandolin woods. I find that 7 to 8 coats, half-mil or so, gives me a great finish, but never more than 6 in a day (usually 5). If there is any open grain, I drop fill or brush after the third coat has cured. Here is a trick for measuring film thickness: get a piece of clear acrylic plastic from a hardward store. Measure it with a micrometer. Spray a normal coat on it and measure it an hour later when it has cured. Do the subtraction and you have your cured film thickness for one pass. Keep doing that for as many passes as you do on an instrument. Measure it after the initial cure and then a week and again a month later, and you will have your coat thickness. To be even more accurate, do a level sanding on it after you have your coats on and buff it then measure and see what the finish thickness might be.

Pete, there are as many finishing schedules as there are finishers. You just need to find what works best for you. What helps is to know how much build you are getting. After the first set of coats dries, you can peel it off the soundhole cover and check it with a micrometer. The main thing is that you are spaying the whole guitar evenly and not consistently spraying one area light. I've found that the best way to assure this is by visible inspection immediately after spraying.

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

I sure appreciate the great info from Randy, Rolfe, and Tom......Thanks! Nice to see you joined and posted just to contribute to this thread.

I must admit, I didn't want to see Tom's response......but I was afraid that freshly dissolved shellac/SealCoat woudn't be the answer under a waterbased Urethane (which is what I understand KTM-SV is) after reading the article I linked to in a previous post above.

Now my dilemma........what can I (an ametuer) use to seal my Indian Rosewood that doesn't cost my $100+? I can probably obtain the Ilva product somewhere (any pointers?), but I will need to buy at least 1 gallon (guessing $60-80) plus the other part (assuming it's a 2 part product) plus shipping which may include hazmat fees. I must confess, I've never tried purchasing products like this. Any chance you can get them through a local paint shop? If I built enough guitars in a year to use up this product it wouldn't be a big deal. Hate to spend $100 and use it on a couple guitars before it goes out of date.

It seems I need an isolante type sealer. Tom and Randy use the Ilva product. Woody mentioned the ML Campbell Exotic Woods Sealer earlier. Chemcraft also offers an isolante sealer. That's the only ones I know about. Is there a chain outlet that carries one of these lines that might be in my area where I could place an order? Any of these products better or worse than another? Any chance one of these could be purchased in a quart container? Maybe Grafted Coatings could start offering one of these isolante sealers for use with this product on exotic woods.

What type of coating is created with an isolante sealer? On the Chemcraft website, it's listed under "Polyurethane". Is it a special polyurethane? Would some off the shelf polyurethane work as a substitute? Likely needs to be a catalyzed poly.

One other queston about an isolante sealer to seal the oils into exotic woods, why wouldn't the sealer be applied as the first step before pore filling?

Edit: Just read that the Ilva Isolanted Sealer is a ployester sealer.

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Formerly known as Adaboy.......

Here is a link to the Product Information Sheet on the Chemcraft product:

http://www.chemcraft.com/index.php?option=com_rokdownloads&view=folder&Itemid=54&id=2191

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Formerly known as Adaboy.......

Darryl, I found a local supplier yesterday who was prepared to decant a couple of litres of each component from their bulk stock for me. I hope you can find someone in your own neck of the woods who is as understanding and helpful. Judging from Tom's comments, the Ilva product is the way to go.

_________________
Cheers
Pete

That would be nice. It appears you really need 3 products to use the Ilva Isolante Sealer:

- TF-25 resin
- TV-19 hardener
- TZ-35 thinner

Maybe I can call Camger tomorrow and see what I can find out. Oh, on the Camger site this is listed as a polyurethane barrier coat even though it was called a polyester product on another website I found off a Google search.

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Formerly known as Adaboy.......

It's a urethane barrier coat that's required under polyester top coats. This probably causes some confusion as it may be called a "polyester barrier coat" since that is a common use for it. The product itself is a catalyzed urethane though. Hope this is clear.

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

Would perhaps the Grafted Coatings sanding sealer work?

Hi everyone,

It’s been brought to our attention that KTM-SV doesn’t stick to standard shellac and especially direct to exotic woods. (This based on above postings)

Through the help of Rolfe’s post, it’s apparent that sealcoat from Zinsser is an answer along with this isolante sealer for wood.

We were called earlier this week about the issue and until then, we didn’t know the problem existed.

KTM wood sealer is a waterbased acrylic that seals the pores - no guarantee that it will block the oily leeching coming from the wood.

At this time, I am looking into the problem - unfortunately things take time. Once a possible product is made, then tested, etc = additional time so we don’t sell a product that will fail.

http://www.forumsamerica.com/Crafts/Article/355
THE ROSEWOOD JUNGLE
by Dick Boak, manager of the Wood Division of Martin Guitar Company

"The resins in true Rosewoods can prohibit polyurethane and other oil based finishes from curing. It is best to avoid oil-based finishes on Rosewood. Greater success will be achieved with lacquer. A compatible vinyl sealer is most effective as a first coat in order to hold the resins down. Vinyl is also useful in "sandwiching" mineral spirit based fillers before application of successive lacquer (sanding) sealer and lacquer coats. "

Appreciate the feedback.

Thanks,


Matt Lawrence
Grafted Coatings Inc.

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Matt Lawrence
Formulator/Tech Guy
www.graftedcoatings.com

I had adhesion problems with KTM-SV on shellac,
but then I shot it straight on z-poxy on Indian Rosewood (not sanded back on wood)
and I had no problems with adhesion whatsoever. Nor had I any blushing/coloring problems.
I however polished it by hand.

So is there really any reason sealing z-poxy if it is not sanded back to wood?