Originally Posted by Deep Cat
Love the new finish on that short scale shoulder mounted piccolo bass. How did you do it?
I did the repair work to it first - never strip/refinish until the new stuff is in place and instrument glued together. With hide glue you don't want any finish between it and the wood.
I then tried stripping with brush cleaner and elbow grease - no go. It got some but whatever black goo was used to "refinish" before was stubborn. I then switched to citrustrip, now that is some good stuff. The first time I applied and and let set overnight. Subsequent times were just long enough to allow me to scrape more off - a couple hours or so. I think I did it 4 times, until I had enough off to be satisfied that it wouldn't be too dark. I did not try to get all the black out of the top. The black had leached into the wood and I would have had to either sand it out (bad idea, they are thin to start with and you can ruin the tone) or bleach it. I didn't have anything on-hand strong enough to bleach it (and diy concentration of hydrogen peroxide seemed a bit scary and time consuming), so I left some of the black - call them age spots
With that much striping you have to put a new ground layer on. After much research and penny pinching, I found a simple formula of .... SUGAR. Yep, I used 3 teaspoons of light brown sugar. Heat it slowly
by itself until it melts down then keep stirring as long as you can handle it. Get it as dark as possible or the result will never dry and it'll remain sticky. Have some water boiling nearby to add to it.
Why cook the sugar? You have to get all the water out of it before you add water. Sounds odd, but when the boiled water evaporates the sugar goes back to what is was before you added it. So, cooking the sugar crystallizes it and it will be hard after the water evaporates. In the water I boiled in some black tea for coloring ( can do this before or after adding it to the sugar, but easier before). This is what gave most of the golden color to the fiddle. Extra long cooking of the sugar will add color, but the tea enhances it more. When you poor the water into the sugar, do it very slowly - too much at once and it'll foam up making a big mess. Yep, I had to clean up my first batch.
Then you just wipe it on, as many layers as it takes to get what you want. If it is lightly sticky no matter how long you wait, simply wipe the sticky off with a damp cloth and re-coat. I did about 5 layers before I was happy with it.
Now you say: "But sugar will wash off". Yes it will, until you bond it. (makes for an easy fix if you didn't cook the sugar long enough - just wash it off and try again). You bond it with a thin mix of varnish and mineral spirits. I did 25 parts spirit to 1 part varnish. Let it cure completely. I did this in 4 layers. I am no chemist so the 'how' this bonds in the sugar, I don't know.
My final finish was about 6 coats of 50/50 mineral spirits and varnish applied with a lint free cloth. Apply second layer as soon as the first one sets. If you wait too long (several days) you will need to go over it with your varnish solution and 0000 steel wool - then apply your next layer.
If you want a dull sheen, then on the final layer when it is just barely sticky, use a cloth on the tip of your finger dipped in varnish and a drop of mineral oil then rub the whole surface down. I did it circular for spreading then ended with following the grain.
If you want glossy, wait until it's fully set, use your 0000 dry to polish down the bumps. Or use 4800+ sandpaper - I have bad luck with sandpaper for this so I stick with the steel wool. Apply your next layer and let it set. Repeat until you have a mirror/glossy finish. you have to balance how much you apply in each layer, too much and you get puddles and runs. not enough and it'll take many more layers to get the result you want.
Disclaimer; I in no way imply that I did things the best or most productive way. I did what felt right for me with what I had on hand to work with.