Top Tearout

The Achilles' Heel of Luthiery
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mjmeehan
Posts: 191
Joined: Fri Aug 28, 2009 8:58 am
Location: Bethlehem, Pennsylvania

Top Tearout

Post by mjmeehan »

I've had some tearout on the top, near the waist. It's not too bad and I can live with it. However, I'm going to begin my finishing process soon and am concerned about leveling that spot.

Once I begin spraying how do I fill the depression in the finish that is going to occur? If I had to guess I would apply most of the lacquer, drop fill with CA, dry and level, lacquer again, then polish.

Any thoughts?
Tony_in_NYC
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Joined: Thu Aug 12, 2010 9:11 pm

Re: Top Tearout

Post by Tony_in_NYC »

Ken Cierp advised me to let the lacquer start to gel up on a piece of glass or something like a granite tile. Once it gels up, you can use it to fill the depression.
I used the same trick on my headstock. I used highly spalted maple which is very soft unless stabilized with something. I used thin CA but evidently not enough in one spot. I accidently sanded a depression on one end ( I aint saying which end) and in order to get it up level with the rest of the wood, I just filled the depression with gelled up lacquer. It worked like a charm.
I used the same trick to fix a ding on my brother's guitar. Gelled up lacquer into the dent, let dry, sand and buff. You cant tell the ding was ever there, nor can you tell I fixed it. Perfect in every way. If only the rest of my work was like that! LOL
Ken C

Re: Top Tearout

Post by Ken C »

How big is the area? Is it small enough to drop fill or do you have a large depression? If it is small, I'd drop fill with whatever finish you are using after you get a couple of coats on. If it is larger, I'd probably get my first coats down then spray more finish coats over that area to build it up. Level with a good block, and keep filling until you have the area level. Then I'd build up the remainder of my topcoats.

If you are missing a sizeble chunk of wood, you may want to glue in a sliver to fill the void. That would likely be more invisible than a big gap filled with lacquer. You could also make some sawdust from the wood you used for the top, mix it with lacquer, and pack it into the hole. When cured, sand level, and repeat until the gap is filled. I haven't done this building guitars, but it is an old cabinet maker's trick to filling nail holes, and I have used it many a time on furniture and cabinets.

Ken
mjmeehan
Posts: 191
Joined: Fri Aug 28, 2009 8:58 am
Location: Bethlehem, Pennsylvania

Re: Top Tearout

Post by mjmeehan »

Luckily when I routed for the purfling it "ate up" the deep tearout. I think I'll be in good shape drop filling with lacquer. Neat trick, thanks.
I find it interesting that the more I learn about building guitars the more I learn about repairing them!!
kencierp

Re: Top Tearout

Post by kencierp »

I am going to have to disagree with KenC on this one -- working with light colored woods the best and perhap the only way to make an invisible repair is by using a clear filler -- the thickened lacquer is not really my idea (making it by letting lacquer stand around -- maybe) but LMII at one time (perhaps still) sold such product. I used it for years. Also, a clear heated shellac stick will work -- but that is another skill set to learn. As for using dust and glue -- that works fine (sometimes) on the darker woods but will surely make the defect stand out on spruce or any of the conifers --- the caveat on the dark material is that you must have the wood sealed before making the repair. If not sealed the glue will seal it for you and discolor any place it touches, unfortunately it becomes apparent after you apply finish coats. This is an area where taking time to test your repair process on some scrap will be greatly rewarded.
Ken C

Re: Top Tearout

Post by Ken C »

kencierp wrote:I am going to have to disagree with KenC on this one -- As for using dust and glue -- that works fine (sometimes) on the darker woods but will surely make the defect stand out on spruce or any of the conifers
Actually, Ken, instead of glue, I suggested using lacquer mixed with sawdust. I guess the question is how big is the void to be filled? When I read tearout at the waist, I envisioned a bit grabbing the grain and tearing out a chunk that leaves a void most if not all the way through the soundboard. It just sounded too big to fill with lacquer that would darken and shrink over time. I have used lacquer instead of glue mixed with sawdust many times in the past. The fill tends to be tad darker than the surrounding wood, but often can be very invisible. This approach blends in better than when glues are used or even trying to match using wood fills.

I agree with Ken Cierp, do test on some scrap if you are unsure of what results you will get.

Ken
kencierp

Re: Top Tearout

Post by kencierp »

Mixing saw dust with anything makes the paste and patch opaque and will hide the grain pattern which discolors and disfigures the area --- "clear" (DEEP) patches are common in the wood working and furniture industries, as mentioned heated clear shellac sticks is the standard for restorers. Below is the patch kit I would take to our art shows to do quick dent repairs on site, its a little pricey for the hobbyist. The advantage to the clear shellac sticks is that the patch does not shrink and can be made to look like new in just a few minutes with a little padding lacquer applied. The gel lacquer trick looks just as good once few a layers are completely dry.



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mjmeehan
Posts: 191
Joined: Fri Aug 28, 2009 8:58 am
Location: Bethlehem, Pennsylvania

Re: Top Tearout

Post by mjmeehan »

I think that the lacquer fill fix will be fine. The original tearout was about 1/16" or better deep, but like I said this was absorbed/covered by the purfling, leaving a small and not very deep gash. It'll show a little but it's not the end of the world.
I've had this happen before but only on the back. Then it was a simple fix by mixing up some cement with scrapings and sanding flush. No harm, no foul.
tippie53
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Re: Top Tearout

Post by tippie53 »

the only thing I can ad is that if you use a satin lacquer over the repair , this will deflect the light well enough under gloss to help hide it even more. A finish trick I learned in the repair dept at CF Martin. It works for minor flaws very well.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Kevin Sjostrand
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Joined: Sat Feb 09, 2008 8:06 pm
Location: Visalia, CA

Re: Top Tearout

Post by Kevin Sjostrand »

If you remember the repair I did on a spruce top (old forum archives), it wasn't tear out, but I did a fabulous grain match on a long narrow strip repair. I cut out a strip and used AR glue to glue it in. When dry, sanded it down, and it was not visible. However, when I applied the lacquer finish, the glue line on either side of the strip showed. So perhaps this info will help a bit in your repair tactics.

Kevin
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