Dark spot in sap wood

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Dark spot in sap wood

Postby Ryan Mazzocco » Tue Jul 09, 2019 7:06 pm

This guitar is a commission build. The back and side set was specifically picked out by the customer and then I purchased it. I believed the dark spots in the sap wood near the top and bottom of the back pieces were just left over from the stacking/stickering process and were only surface deep.
set.jpg

but after I joined, glued sanded and thicknessed the set, the spot never came out. I'm down to just under .100" which is fine, I could even go a little more, but it doesn't seem to be sanding out. it's on both sides so I'm afraid whatever it is it's all the way through.
Here's a pic as it is now with some naptha on it. It really pops out like a big black spot, or like an unsightly scuff mark. What is a fella to do?
spot.jpg
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Re: Dark spot in sap wood

Postby John Clifford » Tue Jul 09, 2019 8:01 pm

When all else fails, inlay!

Seriously, if it's on both sides, nothing is going to remove it. There are various wood bleaching chemicals, but you'll never get the color to match the surrounding sapwood. So time to get creative and introduce some other woods. Of course, you'll have to get your customer to buy in. But if you can come up with a really eye-popping design, then it's like they're getting a bonus, right?
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Re: Dark spot in sap wood

Postby Bob Gramann » Tue Jul 09, 2019 10:00 pm

It’s wood. Wood has variations. Personally, I would use it. But, I guess you have to ask the customer.
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Re: Dark spot in sap wood

Postby Mark Wybierala » Wed Jul 10, 2019 12:22 am

Do you have a friend that is good with an airbrush? An artist who can maybe creatively duplicate the dark spot? Faux bookmatch?
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Re: Dark spot in sap wood

Postby Bryan Bear » Wed Jul 10, 2019 8:36 am

It is interesting that it doesn't show up in the bookmatch. They have about 5 sets up on their website with the same dark spots in the sapwood (probably from the same board) but they mostly show on both halves of the sets. I'm sorry, I don't have any advice, I'm just thinking out loud.
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Re: Dark spot in sap wood

Postby Clay Schaeffer » Wed Jul 10, 2019 8:59 am

Careful application of wood bleach might lighten it enough to where it won't draw the eye. The other option might be to stain the sapwood to bring it down to match the stain.
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Re: Dark spot in sap wood

Postby Barry Daniels » Wed Jul 10, 2019 9:27 am

I too was thinking of the stain the sapwood option. It won't hide the dark spot but will tone it down a lot. Q-tips and Transtint would make quick work of this.
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Re: Dark spot in sap wood

Postby Ryan Mazzocco » Wed Jul 10, 2019 9:44 am

Bryan Bear wrote:It is interesting that it doesn't show up in the bookmatch. They have about 5 sets up on their website with the same dark spots in the sapwood (probably from the same board) but they mostly show on both halves of the sets. I'm sorry, I don't have any advice, I'm just thinking out loud.

Yes, that's just the thing. It sanded out quite quickly on the left side. That's why I kept sanding. I was very sure that it would sand out on the right side as well. And I don't believe it's any naturally occurring coloring in the wood as the mark was very quadrilateral in shape on the the raw set. I'm wondering if I should contact Hibdon about this. They're awesome guys and I don't want to give them any trouble, but I'm just not sure this is going to fly with the customer. And if this is a result of their process then they probably need to be made aware of it.
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Re: Dark spot in sap wood

Postby Bryan Bear » Wed Jul 10, 2019 10:11 am

Definitely call them but I don't think it is part of the processing. If you look at the remaining sets on their site, you can see three sets with matching sapwood bands and you can see three similar spots entering and leaving the board as it progresses through the slices. I think it is something in the log. I'm guessing your slices are on the tail end of one of these spots and you were able to sand out the shallow side. I can't get a close look but it looks like the "stain" is dark towards the inside of the tree and feathers out into the newer sapwood towards the bark side. Maybe a someone with more tree knowledge will chime in.
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Re: Dark spot in sap wood

Postby Clay Schaeffer » Thu Jul 11, 2019 12:42 pm

You could try oxalic acid on the spot to see if it will remove it. Looking at the staining on the other sets shown I agree with you that I think it is from the processing of the lumber and not a natural occurrence.
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Re: Dark spot in sap wood

Postby Bryan Bear » Thu Jul 11, 2019 3:11 pm

I'm interested in what makes you think it is from the process and not natural? I could be wall wrong with my initial thoughts. To me it looked like the spots were heavier on one side of each bookmatch and looked to be working its way through the board as some would get larger and some smaller as you went through the slices. That and the fact that it goes all the way through made me not think it was some sort of contamination. Mostly because I don't see how it could work its way all the way through the 1/4" of thickness before it was noticed and an attempt to remove it was made. They saw the slices and after running them through the sander mark each one with a number so you know they are looking at them in real time.

Having said all that, and now with two people thinking it is from the process, I am noticing that on the couple of sets that have part of 3 spots on them, they seem to be roughly equidistant indicating that it could be from a roller of some sort. I would assume from the saw since they would not all line up with the edge of each slice being fed through the sander.

If it is some sort of contamination that has soaked through the wood, you might try flooding it with naptha, and let it flash off a few times to see if it gets smaller. That might work if it is some sort of oily contamination from a roller. Or, I could be way off base. :(

Ryan, make sure you tell us what they say.
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Re: Dark spot in sap wood

Postby Ryan Mazzocco » Thu Jul 11, 2019 4:22 pm

First off, I want to make sure that's I'm not coming across as saying anything negative about the guys at Hibdon. They are super guys that produce a quality product at great prices with superior customer service.
I have been in contact with them and they have confirmed that the marks are from the stacking process. Apparently the little wood blocks they used reacted with the sap wood in the walnut and produced these dark marks. They say it's normal for them to see this. What they don't normally see is for it to go deep enough that it doesn't sand out. After selling about 30 sets with the same marks mine had, I have been the first to contact them regarding the problem. So it could be that my set is the oddball, with the stain so deep that it didn't sand out.
I invited my client over to the shop this afternoon and we discussed it. After looking at the piece through a body template and lots of Naphtha we found a good placement for the spot and he's agreed to move forward.
Still, it does make me nervous about buying more walnut with these marks on it in the future....
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Re: Dark spot in sap wood

Postby Waddy Thomson » Fri Jul 19, 2019 11:30 am

I have some of that wood. No one has complained. A stain of some kind. Does not come out, but hey, it's wood. Wood has all kinds of anomalies. I built one spec guitar with it, and another on commission where he requested that wood and particularly liked the stain.

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