Finishing Problem

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Forum topic by miserybob posted 07-22-2010 03:59 PM 1168 views 0 times favorited 7 replies Add to Favorites Watch
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88 posts in 3014 days

07-22-2010 03:59 PM

Hi all!

The pic is part of a box I’m building to try out a few new inlay and finishing techniques. The finishing part has been a PITA. I’ve used Copperas (ferrous sulphate) before on White Oak, and it turned out a nice, even gray – very pretty, actually. So I thought I’d see what it did to Cherry… not so nice – kinda blotchy and inconsistent. It’s an interesting look, though. The problem I have is the odd, white areas you can see. I didn’t have those on the oak table I did. I used a spray lacquer on the oak table (I had access to a spray booth then) but am brushing shellac on the box.

Any ideas what would cause shellac to do that? It might be a reaction to the chemical stain (in which case I might be out of luck), but maybe it’s something simpler. It has been very humid and hot in the shop lately.

I’ve tried to gently sand it down a bit and recoat (I’ve put on about 3 or 4 coats of 2# blonde shellac), but it shows up in the same areas again.


7 replies so far

View richgreer's profile


4541 posts in 3044 days

#1 posted 07-22-2010 04:46 PM

I’ve not seen anything like that with shellac before and I don’t know what caused it.

However, I have found Charles Neil’s blotch control (pre-color conditioner) to work wonders. I would sand it done to bare wood, apply the blotch control (and stain if desired) and then apply the shellac. I don’t know if this would work, but I think there is a very good chance that it will.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View swirt's profile


2662 posts in 2942 days

#2 posted 07-22-2010 05:20 PM

What happens if you give it a really good rub with just alcohol on a pad? Does the discoloration disappear and then reappear?

Shellac can fog with moisture so it is possibly due to high humidity , but the weird spilling pattern makes it look like something was spilled on it or before it, that it is reacting to.

-- Galootish log blog,

View miserybob's profile


88 posts in 3014 days

#3 posted 07-22-2010 06:05 PM

Swirt – The alcohol takes away the whiteness for a brief time, then it returns, but less than before. What do you think that means? Silly question – is the alcohol dissolving layers of the shellac? If so, I suppose I can just keep going and try a different top coat, like some rattle-can lacquer.


View swirt's profile


2662 posts in 2942 days

#4 posted 07-22-2010 09:12 PM

Yes the alcohol is dissolving layers of the shellac. When you put shellac on, it is dissolved in the alcohol. Each layer sort of melts into the previous. This is what makes shellac so easy to repair.

If you leave a glass with condensation on a shellac finish you will usually get the telltale white ring, but rubbing it with alcohol disolves some of the finish and at the same time allows the water to leave.

My guess would be that your finish had some moisture get into it somehow or possibly in the wood. You can keep rubbing it with alcohol and when the mark or the finish is gone, you could build up more finish … or go with something else.

-- Galootish log blog,

View a1Jim's profile


117063 posts in 3547 days

#5 posted 07-22-2010 09:26 PM

old shellac,possible reaction to the Copperas, It might have helped to clean it with naphtha first.
I think you can still clean it with Naphtha after a lite sanding and recoat with Shellac.

-- wood crafting & woodworking classes

View miserybob's profile


88 posts in 3014 days

#6 posted 07-23-2010 04:36 AM

Thanks, everybody! A combination of rubbing with alcohol followed by naphtha followed by Deft lacquer seems to be working pretty well. Phew. Too much work to throw it out now!

I’ll post it when it is finally finished, whenever that’ll be!


View Rick George's profile

Rick George

48 posts in 3022 days

#7 posted 07-24-2010 02:54 AM

Interestering reading. My problem is similar, but noone responded to my pleas for help. I think I’ll approach my problem as you did and see if things improve. Can’t wait to see the finished product. Good luck.

-- Rick

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