Hard shellac touch ups - pale areas

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lamanoditrento
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Hard shellac touch ups - pale areas

Post by lamanoditrento » Fri Aug 03, 2018 1:23 pm

Well, I had a 2nd bridge failure that after removing the bridge has led me to routing a pocket and inlaying fresh spruce under the bridge footprint. When levelling the new spruce I have sanded through the hard shellac in front of the spruce. Last time I just sanded everything off and started anew. This time I tried to lightly sand the unaffected area on reposhish with heavy attention to the affected area. Now I have refinished the top but now there is a paleness (mostly at oblique angles but not directly on) of the area where I had gone through the old finish.

Anyone know/have any experience with hard shellac and know if the pale area is likely to darken up and blend with the older finish?

BTW, The "old finish" was only 4 or 5 weeks...

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lamanoditrento
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Re: Hard shellac touch ups - pale areas

Post by lamanoditrento » Fri Aug 03, 2018 1:30 pm

It is hard to photograph but you can kinda see it here:
Paleness 1.PNG
Paleness 2.PNG

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56nortondomy
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Re: Hard shellac touch ups - pale areas

Post by 56nortondomy » Fri Aug 03, 2018 4:30 pm

I'm having the exact same problem at the moment Trent, I had a string pull out of a classical bridge and put a ding in the top, so I filled it and when I sanded back went too far and now I can't seem to get it right. I've laid more hard shellac on and I'm waiting to level again. Wayne
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kiwigeo
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Re: Hard shellac touch ups - pale areas

Post by kiwigeo » Fri Aug 03, 2018 5:28 pm

This is something that I've always wondered about with Hard Shellac. Once the stuff has cross linked how easy is it to do repairs to the finish later on down the track. Trevor is probably the best person to consult on this one....any learned advice Trevor? :)
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Crafty Fox
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Re: Hard shellac touch ups - pale areas

Post by Crafty Fox » Sun Aug 05, 2018 2:41 pm

If the "old" finish is only a few weeks old then won't the new finish soon catch up in appearance?
Ken

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lamanoditrento
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Re: Hard shellac touch ups - pale areas

Post by lamanoditrento » Mon Aug 06, 2018 8:05 am

Crafty Fox wrote:
Sun Aug 05, 2018 2:41 pm
If the "old" finish is only a few weeks old then won't the new finish soon catch up in appearance?
That is what I am hoping....

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Trevor Gore
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Re: Hard shellac touch ups - pale areas

Post by Trevor Gore » Tue Aug 07, 2018 1:01 am

If you sanded through to the wood, and took some "sun tan" out of the wood, the "sun tan" seems to take for ever to catch up, if it ever does.

If you just sanded shellac, because all shellac has some tint to it, you have to match the thickness of coating pretty exactly in order to build to the same colour. In theory this is possible. In practice it is very hard to achieve in order to get an exact, totally invisible blend. This adds to the complication of a sand through, of course. I don't think the shellac itself changes colour enough to see over the timescales we're talking about here.

If you're filling minor dings, these can be drop filled with shellac, but because of the colour in the shellac, the filled bit gets darker and the surround can get lighter, unless you level very carefully. You could try drop filling with clear nitro, and I suspect that will give a better result. I'd avoid CA.

I've done a few drop fill repairs on nitro finished guitars, with the results being pretty well invisible. I've only had to do one repair on hard shellac, and that was numerous dings from some accidental damage by a third party, which ended up as an insurance claim. I took the bridge off and stripped the original finish by sanding and refinished the whole top.

If you look at refinished standard shellac on old guitars, they always look pretty patchy colourwise.

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lamanoditrento
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Re: Hard shellac touch ups - pale areas

Post by lamanoditrento » Tue Aug 07, 2018 1:55 pm

Trevor Gore wrote:
Tue Aug 07, 2018 1:01 am
In practice it is very hard to achieve in order to get an exact, totally invisible blend. This adds to the complication of a sand through, of course.

...

If you look at refinished standard shellac on old guitars, they always look pretty patchy colourwise.
...but this is what I feared. Thanks Trevor. I think I will resand and refinish the whole top. I hate the idea of patchy colour on a new guitar.

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