Hairline Cracks in Macassar Ebony Back - FRETS.NET2024-03-29T10:15:23Zhttp://fretsnet.ning.com/forum/topics/hairline-cracks-in-macassar-ebony-back?commentId=2177249%3AComment%3A167539&feed=yes&xn_auth=noFrom what I can see, you buil…tag:fretsnet.ning.com,2017-03-10:2177249:Comment:1675752017-03-10T04:31:25.124ZHoward Klepperhttp://fretsnet.ning.com/profile/HowardKlepper
<p>From what I can see, you built with flatsawn wood containing a wide area of sapwood (or a light heartwood area that looks like sapwood?). There's a good reason that such wood was, until very recently, considered unfit for guitar building. And it developed multiple cracks before you were done finishing. I would be worried that the problem will be ongoing. How level is the back now? How about a couple of photos that show the whole back?</p>
<p>From what I can see, you built with flatsawn wood containing a wide area of sapwood (or a light heartwood area that looks like sapwood?). There's a good reason that such wood was, until very recently, considered unfit for guitar building. And it developed multiple cracks before you were done finishing. I would be worried that the problem will be ongoing. How level is the back now? How about a couple of photos that show the whole back?</p> Yes. Shellac is a great seal…tag:fretsnet.ning.com,2017-03-08:2177249:Comment:1674652017-03-08T18:27:44.679ZRobbie Collinshttp://fretsnet.ning.com/profile/RobbieCollins
<p>Yes. Shellac is a great sealer. It can marry many disparate materials that otherwise cause adhesion problems. Nitro doesn't much like poly, CA, epoxy or silicon and shellac will make them friends. I always use it and, if you're doing a clear finish, it adds a lovely vintage vibe. Canned shellac is okay if you make sure it's dewaxed and you check the date. It needs to be fresh. I always mix my own using fresh flakes from shellac.net and Everclear grain alcohol for the solvent.…</p>
<p>Yes. Shellac is a great sealer. It can marry many disparate materials that otherwise cause adhesion problems. Nitro doesn't much like poly, CA, epoxy or silicon and shellac will make them friends. I always use it and, if you're doing a clear finish, it adds a lovely vintage vibe. Canned shellac is okay if you make sure it's dewaxed and you check the date. It needs to be fresh. I always mix my own using fresh flakes from shellac.net and Everclear grain alcohol for the solvent. Shellac.net has a lot of information for newbies, though you'll have to browse a bit to find it. There is also copious info on YouTube.</p> Thanks Robbie. I have scrape…tag:fretsnet.ning.com,2017-03-08:2177249:Comment:1675742017-03-08T14:37:37.364ZPhilip Secristhttp://fretsnet.ning.com/profile/PhilipSecrist
<p>Thanks Robbie. I have scraped and sanded the finish back to bare wood. I am going to try the epoxy method Frank suggested to fill any other unseen cracks and give the back a "fighting chance". After doing this, would you recommend spraying a coat or two of fresh shellac before starting with the nitro top coats? Thanks!</p>
<p>Thanks Robbie. I have scraped and sanded the finish back to bare wood. I am going to try the epoxy method Frank suggested to fill any other unseen cracks and give the back a "fighting chance". After doing this, would you recommend spraying a coat or two of fresh shellac before starting with the nitro top coats? Thanks!</p> Hey Frank, I have scraped an…tag:fretsnet.ning.com,2017-03-08:2177249:Comment:1675732017-03-08T14:34:08.914ZPhilip Secristhttp://fretsnet.ning.com/profile/PhilipSecrist
<p>Hey Frank, I have scraped and sanded off the finish on the back down to the bare wood. I would like to apply epoxy to give the back a fighting chance. When mixed, my system III epoxy is of honey consistency. How much do you think I should thin it with acetone to give it the best chance of penetrating into any unseen cracks? </p>
<p>Hey Frank, I have scraped and sanded off the finish on the back down to the bare wood. I would like to apply epoxy to give the back a fighting chance. When mixed, my system III epoxy is of honey consistency. How much do you think I should thin it with acetone to give it the best chance of penetrating into any unseen cracks? </p> I second Robbie's suggestion.…tag:fretsnet.ning.com,2017-03-08:2177249:Comment:1677812017-03-08T05:59:37.679ZGreg Mirkenhttp://fretsnet.ning.com/profile/GregMirken
<p>I second Robbie's suggestion. Sand it back and shoot a coat of Zinsser SealCoat shellac.</p>
<p>I second Robbie's suggestion. Sand it back and shoot a coat of Zinsser SealCoat shellac.</p> Try a coat or two of fresh sh…tag:fretsnet.ning.com,2017-03-08:2177249:Comment:1674642017-03-08T00:13:48.773ZRobbie Collinshttp://fretsnet.ning.com/profile/RobbieCollins
Try a coat or two of fresh shellac if you adhesion problems.
Try a coat or two of fresh shellac if you adhesion problems. Thanks Frank. I was looking…tag:fretsnet.ning.com,2017-03-07:2177249:Comment:1676532017-03-07T17:16:19.652ZPhilip Secristhttp://fretsnet.ning.com/profile/PhilipSecrist
<p>Thanks Frank. I was looking for an easier way to do this and may have gotten myself into more trouble. :( I tried just filling the cracks with thin CA from the finish side and cleated in the inside. I scraped the repairs flush with the finish with a razor blade with scotch tape on the sides (or though I had sufficiently) and sanded the entire back level with 220 grit, and then resprayed the back. I couldn't see the CA around the cracks or feel the repair before I sprayed, but here is…</p>
<p>Thanks Frank. I was looking for an easier way to do this and may have gotten myself into more trouble. :( I tried just filling the cracks with thin CA from the finish side and cleated in the inside. I scraped the repairs flush with the finish with a razor blade with scotch tape on the sides (or though I had sufficiently) and sanded the entire back level with 220 grit, and then resprayed the back. I couldn't see the CA around the cracks or feel the repair before I sprayed, but here is what I saw after spraying one coat of nitro on the back. <span style="text-decoration: underline;">See pic.</span> It appears that the new finish did not flow over the crack repairs and conglomerated on the edges of where the CA was applied (which obviously didn't get scraped down enough). So, I dropped filled the crack several times over a day and then scraped the area flush the next day and re-sanded the back to get it all level, and shot the back again with another coat and.... I still see the same thing. The finish is not flowing over the repairs. So, now I am wondering how to proceed. Could I sand the entire back down just enough to remove the excess CA around the cracks, or do I need to go all the way to the wood and do as you first suggested? Thanks Frank.</p> I'd stay away from solvents a…tag:fretsnet.ning.com,2017-03-04:2177249:Comment:1674562017-03-04T15:47:02.584ZFrank Fordhttp://fretsnet.ning.com/profile/FrankFord
<p>I'd stay away from solvents at this point, for fear of driving more contamination into cracks. I'd scrape and sand carefully dry, blow of the dust as well as I could, then proceed with the CA and epoxy, doing the same with each layer of that stuff, too. Nasty work, for sure.</p>
<p>I'd stay away from solvents at this point, for fear of driving more contamination into cracks. I'd scrape and sand carefully dry, blow of the dust as well as I could, then proceed with the CA and epoxy, doing the same with each layer of that stuff, too. Nasty work, for sure.</p> What I was saying is somewhat…tag:fretsnet.ning.com,2017-03-03:2177249:Comment:1677642017-03-03T21:31:11.411ZRussell Vancehttp://fretsnet.ning.com/profile/RussellVance
<p>What I was saying is somewhat moot, Franks epoxy soak seems like consensus - but the same issue arises. The epoxy or thin CA will seep through the cracks and drip into the box so you can either tape up under the noticeable cracks, or put some filling inside to catch the drips. Taping up is a problem if the glue attacks the tape and sticks the whole lot together so use brown plastic packing tape which tends to not let either epoxy or CA stick to it even with the adhesive side to the…</p>
<p>What I was saying is somewhat moot, Franks epoxy soak seems like consensus - but the same issue arises. The epoxy or thin CA will seep through the cracks and drip into the box so you can either tape up under the noticeable cracks, or put some filling inside to catch the drips. Taping up is a problem if the glue attacks the tape and sticks the whole lot together so use brown plastic packing tape which tends to not let either epoxy or CA stick to it even with the adhesive side to the glue. </p>
<p>As far as softening the finish before removal with a solvent or retarder - I'm hesitant as I have in the past managed to get it on the "good stuff" that I didn't want to remove - acetone used to damp a terry cotton cloth works on nitro. - which is the same as using thinners. I use heat gun for most solid body nitro removal but that's not an option her with the thin unstable back we are talking about.</p>
<p>Tell us how you went with this, it's a good learner for me.</p>
<p>R.</p> Thanks Frank. Any recommendat…tag:fretsnet.ning.com,2017-03-03:2177249:Comment:1674492017-03-03T01:45:46.770ZPhilip Secristhttp://fretsnet.ning.com/profile/PhilipSecrist
<p>Thanks Frank. Any recommendations on nitrocellulose lacquer softener so I can scrape it off? I realize there are no guarantees with any process. :) Thanks again!</p>
<p>Thanks Frank. Any recommendations on nitrocellulose lacquer softener so I can scrape it off? I realize there are no guarantees with any process. :) Thanks again!</p>