Spraying the top and "sap lines" showing up

[Kevin Sjostrand]

This is the first time it has happened to me, but I have to imagine I'm not the first person it has happened to.
My top these lines, random, dark like a grain line, that the lacquer sank into while spraying. At first I thought I had left deep scratches in the top, but I said to myself, "NO WAY". I did plenty of sanding up to 240 grit through out my process. After I sprayed a few coats, and level sanded, I was able to come down in these areas past the shiny lines, and had a perfectly flat, dull surface. These are in the center area on either side of my seam where the grain lines are tighter, various lenths and above and below the sound hole, and below the bridge area. None are out in the wider grains area in the bouts.
When I sprayed a couple of coats again, they showed up again, but again, I was able to sand flat and there is for sure they are filled.
Strange. Have you all seen these before in any of your tops? Is it like sap, or pitch pockets?
I don't mind the look, but sure didn't see them before I started spraying.

Kevin

[johnnparchem]

I have had that on a glue line in the back. I have not had it happen on the top. One thought, I sand my spruce tops against the grain. The light and dark wood are different hardness and will sand at different rates. When sanding with the grain it is easy to sand in some wash board. My thought, and I am just making this up, is that while you sand the top finish level, it is still curing and the finish is still shrinking at a pretty good rate. If the wood top has this slight wash board while the finish is still shrinking it will show up, as the deeper finish will proportionally lose a bit more depth relative to the shallower finish. My guess would be that after three or so weeks when the top has stopped shrinking and you sand out the differences it will stay sanded out.

[B. Howard]

Can you post some pics? Need to see just what we have here.

[Kevin Sjostrand]

Definately not the washboard affect going on John, but I know what you are taking about there.
I'll shoot some pics and post them tonight. I sprayed my finish coats this morning and I suppose as they dried the lines may show again.

Kevin

[Kevin Sjostrand]

This pic shows them pretty well. I've sprayed more coats, sanded back, and sprayed more sense this picture and they are getting better.
Can you see the lines, like the grain, and in one area you can see how it is not totally level, although the lacquer has filled the area.

Kevin

[Darryl Young]

Wha tkind of sealer did you use on the top?

[B. Howard]

The spot I see in the pic looks like tear out from the binding tape. Spruce can be stringy and these little pull ups of wood will show through you need to build enough material to fill them so they can be leveled and buffed. You could fill them with clear burn in stick and then put down another couple of coats.

[Kevin Sjostrand]

Mohawk vinyl sealer, mohawk stringed instrument lacquer.
Pretty sure its not from pulling up tape as these are up and down the center section of the top, as much as about 3 in on each side of center, not really around the perimeter as there would be with the use of binding tape.
I've sprayed two more heavy coats this morning, and these are beginning to fill level. They are in the wood, tan lines that look like the darker grain lines.
They will be filled, but I just have not experienced them before.

Kevin

[B. Howard]

I had some sitka a while back that had pores almost big enough to be filled. It was a PITA to french polish. But that looked different then what I saw in the pic and it was fairly even over the whole top.

[Kevin Sjostrand]

I think I got a morphadite top here.......