How to start a french polish over?

[dingoguitar]

I built an acoustic and french polished it, it turned out okay, but not amazing. I'm working on my second guitar when my daughter indicated she wanted a purple ukulele.
I bought a cheap kit online and thought this would be a great chance to play with dyeing wood and practice my french polishing technique with very little cost risk.

I wanted to try pore filling with timbermate. I pore filled before dyeing and got what I thought was a nice level surface, then dyed it a nice purple. I began putting shellac on and noticed the mahogany was not filled at all. Maybe the water in the dye removed the timbermate, not sure. I assumed I should fill before dyeing.

I have pumice so I tried to fill the pores with this, but don't really know what I'm doing. I see lots of tutorials online but they're all a bit different. This a is great chance to practice. The tutorials say that pumice should make the surface flat. Mine always looks cloudy (which means it's not flat, it's rough)
Should it get shiny and reflective? during this pore filling, my pad is only charged with alcohol and a tiny bite of pumice - spread around. Do I spend 20-30 minutes continuing to rub this in? or is it a 2 minute deal?

I somehow got some craters in the finish and wanted to sand it back. I used 400 grit, it gummed up and got much worse and the sanding removed some of the dye from the back edge. I cannot seem to redye this, probably because there's still some shellac on. I want to fully remove the shellac add more dye and begin the coating process again. What's the best way to do this? I tried washing off the shellac with pure alcohol (don't think it worked).

Only the back is messed up and need redyeing
Should I just pull out the orbital sander and 150 grit? or is there a better way?

Has anyone found a single tutorial that tells you what you need? This set is great, but when he pulls out his guitar, it already has a wash coat and is flat. Plus there's no pore filling.

Just looking for some suggestions and discussion.
Thanks in advance!

[Ned Milburn]

The real key, I believe, to French polishing (including pumicing) is balance of the elements. The elements that need to be balanced include:

- shellac
- alcohol
- pumice
- oil
- pressure
- time

Even a little too much of any one element can make the process painfully slow and can yield little to no progress.

For pumicing, you will want to make certain there is already enough shellac ON THE INSTRUMENT if you are using ONLY alcohol. Otherwise, you will need a weak mix of shellac, and this can be alternated with straight alcohol when you get too much build. Don't expect to fill one area before moving on. Rather, try an additive approach working in patterns to cover the whole instrument, before beginning to go over the whole instrument again. If you work too much in one area, you are more liable to get inconsistent results with patchiness of colour and build thickness.

If you are getting a cloudy finish, you are likely using too much pumice. Use only a touch, and use it until it no longer fills the pores.

The most efficient way to pumice fill is to work up a slurry - specifically, a mix of shellac, alcohol, pumice, microscopic wood fibres, and wood dye that absorbs into this mix. Getting a slurry like this takes some effort, but you should be able to see it and even squeeze some off the surface of your pad.

Patience and frugal use of the elements (except liberal with time) is key.

Hope this helps.

[B. Howard]

I recommend scraping to remove the bulk of the finish and then sand.

[Quickstep192]

I have removed shellac by applying denatured alcohol. It's one of the things i like about shellac. If it doesn't turn out the way you like, you can take it off and start again. Because the alcohol evaporates so fast, it's can be hard to keep the surface wet long enough to make the shellac dissolve so you may need to apply very liberal amounts of denatured alcohol. Do keep in mind that by slopping the alcohol around, you're creating vapor from a solvent that is very flammable to begin with and burns without a visible flame. Be Careful!

[dingoguitar]

Great, I just gobbed alcohol on a rag and wiped it off, resanded the back, redyed it and have shellac going back on nicely.
Looks great.

Thanks for the tips on the pumice. That helps too and it's going pretty well however the sides of a ukulele are so small and hard to get any pressure while holding the thing still. I may leave the sides less than mirror-like