Lacquer Delamination Issue

When I moved from using Tru Oil finish to lacquer I used rattle cans from the hardware store for a couple of ukes. I had a small amount of lacquer that chipped away right at the edge of the fretboard. Thought it might be the fact I wasn't using a product intended for instruments. I’m finishing up a few ukes now sprayed with Seagrave lacquer and I’m still having some issues.

I tape the FB before spraying and if I can’t get back to it in a timely manner I remove the tape after a couple days and put new tape on before the next session.

I see incredible finishes on instruments from Chuck and Beau etc. Do any of you guys ever experience this problem? I’m convinced I’m doing something wrong.

I experienced this earlier this year for the first time on a guitar but only on one side of the fingerboard, all along it and only on the fingerboard wood. I think it may have had something to do with heat build up from me radius sanding the FB (I do 16" on guitars) but i'm really not sure. It may have been abnormally oily Maccassar ebony, or bad bond to ca glue from the side dots, or from the oil based grain filler not wiped away good enough.

I feathered the ledge off with sand paper and re sprayed and all was well, but I strung it up a few weeks later then I wanted.

As it didn't delaminate anywhere else, I think it was definitely something I did (or didn't do) but i'm not sure which element is to blame- probably a combination of ebony and oil based grain filler residue???

I was using Durabond Nitro which is a local Sydney company.

I've had it happen to me but it was from getting the lacquer on too thick there at the edge and while I was scraping the over spray that leaked over on the the fretboard, it chipped. Haven't had it happen any other time. I'm using the Cardinal Gloss these days. Lacquer from the hardware store could be another whole set of problems. I've used Dunn-Edwards lacquer on cabinets and doors with great success but never on an instrument.

Beau Hannam Ukuleles said:

I experienced this earlier this year for the first time on a guitar but only on one side of the fingerboard, all along it and only on the fingerboard wood. I think it may have had something to do with heat build up from me radius sanding the FB (I do 16" on guitars) but i'm really not sure. It may have been abnormally oily Maccassar ebony, or bad bond to ca glue from the side dots, or from the oil based grain filler not wiped away good enough.

I feathered the ledge off with sand paper and re sprayed and all was well, but I strung it up a few weeks later then I wanted.

As it didn't delaminate anywhere else, I think it was definitely something I did (or didn't do) but i'm not sure which element is to blame- probably a combination of ebony and oil based grain filler residue???

I was using Durabond Nitro which is a local Sydney company.

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Hmm....come to think of it this has only happened with ebony fingerboards. No issue on a uke with rosewood FB. And this particular one I'm having the issue with now it is only on the one side of the FB also.

Are you sealing before lacquer? Most lacquers don't adhere that well to bare wood.

Anyone used DEFT lacquer??

http://www.idealtruevalue.com/servlet/the-17611/13-OZ-Aerosol-Clear/Detail

Well, I've never used Deft but I have used this

hahahah..........

Beau Hannam Ukuleles said:

Anyone used DEFT lacquer??

http://www.idealtruevalue.com/servlet/the-17611/13-OZ-Aerosol-Clear/Detail

Click to expand...

I have used Deft on cabinets and wooden boxes, but I would never use it on an instrument. In my experience Deft is too soft and is easiley scratched.

Good to know- Thanks BlackBearUkes- a mate told me about it 2 days ago, first time id heard of it. Ive used reRanch before which was pretty good and I saw a sunburst guitar finished with stewmac aerosols which was good too.

Sorry Dom, I've never had the problem. I only sand to 220 after the filler in the belief that this encourages better mechanical adhesion. What kind of filler are you using and are you letting it dry thoroughly before applying the sealer?
And I agree with others re Deft or Watco rattle can lacquers. Very high solids content and it never drys very hard.

Ditto the Deft comments. It never dries hard enough to rub to a gloss, it just smears. I've very seldom used a sanding sealer under lacquer, and never had an adhesion problem, but I rarely spray over ebony. Sanding to 220 grit is plenty under hard finishes, but under oil or wiping poly I sometimes sand it in with 320 to partially fill the pores (and totally fill them if I get lucky). I've used many gallons of Parks nitro on instruments and like it. Its cheap (though I haven't bought any in years) and available at Ace Hardware on special order. Instrument grade nitro is easier to apply but three times the price (but as stated, I'm somewhat out of date on this).

Thanks for the input gents. I have not been using a sealer. I used Z-Poxy as a pore filler but not for the edges of the FB where the issue is.

Dom, do you think that the lacquer could be pulling away from the edge due to a 'less than ideal' release of the tape when it was removed, where the masking meets the finish? Tape can pull up lacquer when unmasking. Was the edge of the lacquer perfectly intact after the tape was pulled? Was the 'rough ' edge of the lacquer dressed down after the masking was pulled? Unless the edge was contaminated, without seeing the damage you are speaking of, my first thoughts are with mechanical damage. Maybe you could post a pic of the delamination.

There are just far too many types of lacquer out there made by various companies that have been formulated to meet specific needs to comment on which is best etc. Some come pretty close to ready to spray, others are not anywhere near ready to go out of the can.

In Australia we have a far more limited selection than in the USA, but thankfully there are a couple that are ideal for instruments. The one I use I thin 100% and in that mix is between 5 and 10% extra slow thinner or retarder. This allows me to apply thin wet coats that will penetrate into the wood, giving a very strong bond. The following coats stay wet and melt into the underlying layers. As well, they flow very well, so I'm not left with an orange peely finish that requires heaps of sanding to level out.

Keep in mind that lacquer has mostly a mechanical adhesion bond to wood. So never sand wood finer than P320 if you are going to apply lacquer.

If it is pulling away from the wood, then it's one of a few options.

• Sanded too fine
• Contaminated
• Product drying too fast (requires retarder)
• Product too thick (requires more thinners)

You go through the list as a process of elimination. If you didn't sand it too fine, then was there contamination? If not was the product going on wet? If so, then I'd say that it was to viscous (thick) and it's not penetrating and adhering to the wood.

Now, when lacquer is applied in layers over itself, we get a chemical adhesion bond, if applied within 24 hours. After 24 hours the finish can become too hard to rely on the new layer melting into what you have already applied so you need to have some mechanical adhesion as well. If you are applying lacquer in multiple spray sessions over days or weeks as many of us do to get a high gloss finish, then sanding no coarser than P400 and no finer than P800 is the go.

If it is delaminating (coming off an underlying layer of finish) then the list is usually falls into this one.

• Too long between coats without sanding (more than 24 hours)
• Contaminated
• Product drying too fast (requires retarder)
• Product too thick (requires more thinner)

And it turns out that you go through the list as a process of elimination just like the previous one.

resoman said:

Well, I've never used Deft but I have used this

View attachment 62257

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THERE's your problem!

Thanks again for the input. Allen, that's some great info. It's probably a result of a couple things in your list.

Chris, I did use a small flat needle file to smooth the edge where the tape meets the FB prior to removing the tape which seems to help because this time the issue is not near as bad as one time in the past where I just pulled the tape without feathering the edge.

Kent Chasson said:

Are you sealing before lacquer? Most lacquers don't adhere that well to bare wood.

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I've been questioning myself on this and wanted to follow up. When I was using Nitro (many years ago), I was following the Michael Hornick method outlined in an article in the original LMI catalogue. In the article, he said that one of the reasons to use sealer was that nitro didn't bond well to bare wood. Since posting this, I've gone back and read other articles that call that a myth. Not sure where the truth lies.

sealers are not all created equal, some are easier to sand, and some have better 'holdout' than others. Sealers that sand easily are usually weaker than the lacquer itself. I like shellac as a sealer, it sands well, adheres well to about anything, is a great base for about any finish, has great 'holdout', and shellac allows the depth of the wood's color to come through. In my experience, nitro sanding sealers, or straight nitro over wood, given a couple or more years, do not have the same richness of color that shellac on wood does. When grain filling with epoxy or CA glue, this is a moot point anyway. The only problems I have ever had with shellac was with cross contamination when sharing equipment with nitro, or when too much shellac was built up underneath, and maybe not given sufficient curing time, and 'alligatoring' was the result. Also, shellac really likes a full day of cure time before top coating with nitro, though I have pushed it many times without problems.