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Recurring delam(s)
http://www-.luthiersforum.com/forum/viewtopic.php?f=10137&t=55781		 Page 1 of 3
Author:  flemsmith [ Sun Jul 23, 2023 10:26 am ]
Post subject:  Recurring delam(s)
Second guitar, previously reported delams (which I originally called blush) at most all locations where a seam covered titebond original glue. At the time I didn't know enough to seal the surface before lacquer. Used Cardinal lacquer, pore filled with Z-poxy, binding attached with CA, where I have no delams. I decided to strip and try again. Good news is I think I finally understand what levelling really means, which is a big positive for me.
I sanded all the delam areas back to bare wood (the rest of the body was sanded with 150), used Zinzer shellac as a sealant, and started the lacquer process again. Thought I was ready for the final coats...
Image
...and noticed I have the start of the same problem in the rosette (dammit). So, obviously I need to sand at least the rosette back to flush, reseal with shellac and try to build the lacquer back in that area.

Is there anything else I could do to keep the delams at bay as I start yet another repair attempt? Appreciate any and all thoughts. Roy
Author:  phavriluk [ Sun Jul 23, 2023 2:07 pm ]
Post subject:  Re: Recurring delam(s)
If that rosette was installed with Titebond, there may be some amount of hope. Titebond can be heat-activated, so that judicious use of a clothes iron, or even better, a model aircraft 'covering iron', might get the rosette to set back down. Wouldn't cost anything to see.
Author:  Glen H [ Sun Jul 23, 2023 2:29 pm ]
Post subject:  Re: Recurring delam(s)
Roy, is that wood or finish puckering up?
Author:  Hesh [ Sun Jul 23, 2023 4:24 pm ]
Post subject:  Re: Recurring delam(s)
Be sure the Zinser is the dewaxed variety it comes two ways.
Author:  joshnothing [ Sun Jul 23, 2023 5:05 pm ]
Post subject:  Recurring delam(s)
I think for your next guitar you may also need to revisit your process for gluing these decorative components in the first place - that rosette looks like it’s no longer stuck to the substrate in the area of the puckering and has popped up. Is there movement when you press on the areas?

If so, sanding the loose bits down might not be the best way forward - you could end up sanding right through the rosette. Definitely worth trying the suggestion of using heat to try and re-glue it.

Another option - if you liberally applied Titebond when first gluing the rosette then the soundboard endgrain in the trench is probably well sealed and you may be able to wick thin CA in to stick the rosette back down without any staining. But there’s always some risk with CA and softwood endgrain…
Author:  flemsmith [ Sun Jul 23, 2023 6:20 pm ]
Post subject:  Re: Recurring delam(s)
yes, the wood itself has lifted. I'll try using an iron. Not something I've done before. I'll try googling and see what details I can learn.

dewaxed Zinsser...? I don't see anything on the label that says it is dewaxed. Just bought it at Home Despot. I do have some shellac I made from flakes, but not where I am now; trying to stay out of the heat in the desert. Trying to use CA presupposes I'm gonna have to strip the lacquer, right? Will probably try some heat with the tip of an iron first.

Thanks for inputs I had not thought of before. Roy
Author:  rbuddy [ Sun Jul 23, 2023 6:53 pm ]
Post subject:  Re: Recurring delam(s)
The Zinnser Shellac that's called Sealcoat is dewaxed and says so on the can, the other versions of their shellac are not.

By chance did you use the Zinnser Shellac in the rosette recess? Dewaxed is sometimes used to prevent CA bleed into the spruce. Some glues will not bond even to dewaxed shellac, CA being an exception.

If shellac was used to seal the recess for the rosette, you may have to remove the rosette, clean the recess of glue and shellac and redo the rosette.

Sorry if I'm the bearer of bad news but I think it's fixable. Some times it's better to just fix the issue rather than try to patch it up only to have it recur and you're back to square 1 again. That gets really frustrating for me.

Good luck, Brian
Author:  flemsmith [ Mon Jul 24, 2023 10:28 am ]
Post subject:  Re: Recurring delam(s)
No, I did not use any sort of sealer inside the rosette recess; at the time I didn't understand the need for a sealer. I did use it on the top of the rosette wood after removing lacquer and resanding to bare wood the areas with delams, thinking that would allow me to respray lacquer without seeing further problems. Since the delams don't typically appear all that quickly, I'm wondering if what I see now is just the start of worse problems to come. Think I might wait for a spell and see if I have worse (or more) problems appearing before I jump into trying to fix this poor guitar again. Roy
Author:  Barry Daniels [ Mon Jul 24, 2023 11:02 am ]
Post subject:  Re: Recurring delam(s)
What did you use to strip the original finish with?
Author:  flemsmith [ Mon Jul 24, 2023 5:59 pm ]
Post subject:  Re: Recurring delam(s)
lacquer thinner, generic
Author:  flemsmith [ Mon Jul 24, 2023 6:05 pm ]
Post subject:  Re: Recurring delam(s)
BTW, I can see it starting in at least two other places where it had bad delams before. I'm gonna set it aside for a while and think about what to do differently. And so I can tell if they are gonna grow over time like in the original finish. I don't mind doing it over, but not when I don't really know what caused it and how to be sure I'm fixing it. But any thinking inputs are appreciated, just not pressured due to any time urgency on my part. Roy
Author:  Barry Daniels [ Mon Jul 24, 2023 8:27 pm ]
Post subject:  Re: Recurring delam(s)
Lacquer thinner as a stripper could be part of the problem. It is one of the strongest solvents there is and may degrade glue bonds if it sits there too long.
Author:  J De Rocher [ Tue Jul 25, 2023 12:10 am ]
Post subject:  Re: Recurring delam(s)
I'm puzzled by the way the most prominent ends of the rosette segments in the middle of the photo have lifted. It looks like they are curling upward at the joint with the thin dark radial divider. Are the rosette segments really thin? Does the grain in the segments run radially?
Author:  Barry Daniels [ Tue Jul 25, 2023 8:11 am ]
Post subject:  Re: Recurring delam(s)
This is why I suggested that the lacquer thinner as a stripper was the culprit. It would leak in at the joints of the rosette and first loosen that area. I can't think of anything else that would cause that.
Author:  phavriluk [ Tue Jul 25, 2023 9:21 am ]
Post subject:  Re: Recurring delam(s)
I may have missed the answer - - - what was the glue used on the rosette? Lacquer thinner for sure raises hell with solvent glues like Duco Cement.
Author:  Barry Daniels [ Tue Jul 25, 2023 9:49 am ]
Post subject:  Re: Recurring delam(s)
I think he said original Titebond which is not normally affected by lacquer thinner, but if pure thinner sat on it for some time and seeped into the rosette joint then it might stay wet enough and long enough to affect the glue. Just theorizing here.

Another possibility is some water getting in there, which would certainly loosen Titebond.
Author:  rbuddy [ Tue Jul 25, 2023 10:42 am ]
Post subject:  Re: Recurring delam(s)
What wood are the tiles in the rosette made of and how thick?
Author:  flemsmith [ Tue Jul 25, 2023 1:51 pm ]
Post subject:  Re: Recurring delam(s)
Yes, titebond original glued in the rosette wood, which is Paudak with the pores running in toward the center of the soundhole. Don't remember thicknesses exactly, but the rosette layup was originally somewhere close to 080" and mounted proud of the top by quite a bit; I'm guessing they are recessed 040-050". My record keeping at that stage was nothing to write home about.

So the lacquer thinner I used to get back to bare wood in the areas I had delam is probably causing the current delams I see, meaning unrelated to the original ones, which were probably caused by the fact I didn't know to use a sealer before I started spraying? That makes some sense in that the #3 guitar is not showing these effects (yet), and by that time I was trying to use shellac over all glue seams, although it was the same HD Zinsser not dewaxed. Water would surprise me, although I could have stored the body in it's case in between work, which I'm trying to keep at 25% more or less, remembering I'm in the desert.

So the obvious question is what should I do next, and if it requires some experimentation, I have three areas to try ideas since they are all starting to show: the lower section of the back middle seam, part of the end wedge, and the rosette. Only one spot actually lifted the wood. I'm still thinking it makes sense to wait long enough (?!) to see if the problem areas are gonna grow over time. Also, I don't typically tape over the bridge area before spraying, and on #4 I did not tape the under neck area either. So, second question should I go back to using a chisel to remove lacquer from now on?

As my second, the wood was cheap, and I was hoping to eliminate some build problems I had in the first, unfortunately at this stage I really liked the way it sounded, but the worksmanship is not good enough for an in family give away. Roy
Author:  flemsmith [ Tue Jul 25, 2023 4:34 pm ]
Post subject:  Re: Recurring delam(s)
Didn't think it would matter, but I forgot to mention that the top is cedar, not spruce. Roy
Author:  flemsmith [ Tue Jul 25, 2023 9:40 pm ]
Post subject:  Re: Recurring delam(s)
I just remembered, I had this same problem big time on guitar #1. I ended up just trying to blend the lacquer coverage after cleaning the old lacquer off the delam areas I really don't remember how, but I do know it wasn't lacquer thinner. I'm playing it now, no evidence of the delams it once had, although the top needs to be redone again. But so lacquer thinner was a decision I made without much knowledge, although it worked great as far as stripping the lacquer. So what now? Chisel the lacquer around the known trouble areas? Let it air out for...? Then start over with shellac flake mix as the sealer.??
Author:  rbuddy [ Thu Jul 27, 2023 9:53 am ]
Post subject:  Re: Recurring delam(s)
Since I had 2 padauk guitars on the bench and a box of cutoffs it was easy enough to run a little test. I glued a couple tiles cross grain to a piece of spruce (spruce/cedar shouldn't matter) with titebond clamped over night and cured a total of 36 hrs from glue-up. I even used old 2017 titebond I wouldn't normally use for instrument work.

Then literally soaked the padauk side with a puddle of lacquer thinner and let it sit overnight. No delamination even when trying to separate the woods. Just soaked it again with thinner but I don't expect any change.

I've never had problems with titebond and solvents when used in furniture or instruments.

I'm thinking the problem was with the original bond of the tiles to the top. Maybe the glue skinned over before the rosette got clamped in place.

Still a mystery. I took pictures but they only show wood still stuck together.

Sorry Roy, no answers here. It's starting to look like renewing the rosette glue in may be necessary. I'm not seeing a fix without gluing in a new rosette.
Author:  flemsmith [ Thu Jul 27, 2023 12:45 pm ]
Post subject:  Re: Recurring delam(s)
Wow, Brian, I am impressed that you went to all that effort just because I keep making mistakes and asking you guys why. Right now I'm wanting to let that body sit for I don't know how long and see if it gets worse. If it doesn't, at some time I'll probably want to try again. I quit doing that type of rosette 2 guitars ago. And in the meantime, I'm actually excited about how guitar Number four is shaping up. I have just finished the last spray after levelling and letting it cure now, and I honestly believe I've got a really good start on a better finish than any previous, so my attitude is looking up from how it's been most of this year. I do want to say that I appreciate the way all y'all are so willing to help an old noob. Thanks again. Roy
Author:  Hesh [ Thu Jul 27, 2023 1:00 pm ]
Post subject:  Re: Recurring delam(s)
rbuddy wrote:
Since I had 2 padauk guitars on the bench and a box of cutoffs it was easy enough to run a little test. I glued a couple tiles cross grain to a piece of spruce (spruce/cedar shouldn't matter) with titebond clamped over night and cured a total of 36 hrs from glue-up. I even used old 2017 titebond I wouldn't normally use for instrument work.

Then literally soaked the padauk side with a puddle of lacquer thinner and let it sit overnight. No delamination even when trying to separate the woods. Just soaked it again with thinner but I don't expect any change.

I've never had problems with titebond and solvents when used in furniture or instruments.

I'm thinking the problem was with the original bond of the tiles to the top. Maybe the glue skinned over before the rosette got clamped in place.

Still a mystery. I took pictures but they only show wood still stuck together.

Sorry Roy, no answers here. It's starting to look like renewing the rosette glue in may be necessary. I'm not seeing a fix without gluing in a new rosette.


Thanks for all the effort and the scientific method Brian I for one really appreciate this kind of thing too.
Author:  flemsmith [ Thu Sep 21, 2023 9:22 pm ]
Post subject:  Re: Recurring delam(s)
Back to #2. I let it sit for about a month to see if the dramatic delams might settle down after the lacquer thinner I should never have used. Dang if they didn't, all except for the worst one on the rosette, so I clamped that one after wicking some thin CA. Came right down, but just a bit too low, so worked on that with paint brush lacquer applications. Seemed perfect, but after a couple weeks, the repair lacquer shrunk a bit, so I still need to redo that part again. In the meantime I wanted to try the Hot Hide Glue reattachment of the bridge, which I've never done before...

Image

Will see how well it holds, but so far it seems like the best process I've ever tried for bridge attachment. Mucho thanks for those of you who showed me the way, I had no idea how to use those three clamps.

Meanwhile I had a coupla sand thru's on #4, so that guitar is back in lacquer rework. If I screw it up using the seat of pants method, I'll be back asking for tips. Roy
Author:  flemsmith [ Mon Sep 25, 2023 5:07 pm ]
Post subject:  Re: Recurring delam(s)
Second guitar Bridge popped loose!?! Dammit. Held up of after tuning, but heard a few pops I thought were the strings slipping against the bridge pins.

HHG temp 141F, clamped for 24 hrs, cedar top
Seemed too runny compared to any titebond or fish glue, or one of the you tubes I watched. Should I stop heating at the point I'm first getting a constant stream when I let it drip off the stir stick?

Thought I had chiseled all previous glue off, but I can remember some areas were a bit discolored. Should I rout bridge attach area?
rather than use a chisel to remove old glue? How deep? ? ? Assume that may drive a taller saddle?

This is the third bridge attachment on this top, previous 2 were poor workmanship (titebond) and front edge looking like it was starting to lift (fish glue) Not sure it really was coming up when I removed it. Wood had small torn lifts around the thru holes, replaced one chunk with original, used JB marine weld to smooth other divots.

I'm guessing my prep was not perfectly clean enough...I did the assembly in less than a minute I think, did try to scrape with a razor blade before attaching HHG. Need to figure out how to properly fix this before I do bridge attachment on #4, which is back at lacquer due to sand-thru's. Appreciate any advice. Roy
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