I really wish I had been making some test panels as I went along with this, as Colin suggested. I'm pretty far down the road now tho and it would take a week or two to reproduce what I've done so far. Good lesson for next time.

I'll check out the Tom Bills webinar. Thanks for the tip. I'm letting the guitar rest for a couple of days before sanding so I'm tackling some overdue jobs around the house. It won't break my heart to take some time out to listen to the webinar.

I know the feeling, trust me. Let me ask you a question though. In a year, will you have wished you'd taken that week, or is the current finish something you're happy with?

“Stiffing”

Towards the end of the bodying session.

When your pad starts to run out of shellac.
Instead of adding more shellac you start to only add alcohol and oil.
Not too much of either.
Just enough that the alcohol melts the previous layer and just enough oil that your pad does not stick.

This step will melt the shellac you’ve already added during the bodying session and now you can press harder to level any ridges, ripples or imperfections that were created during the bodying session.


“Spiriting”

Lastly, do some Spiriting to remove excess oil.
“Spiriting” is when you only add alcohol and glide in and out of your surface lightly.
All you are trying to do here is to remove oil.
Let the pad dry out.
At first, do not press hard during this step.
Here, as the alcohol evaporates from the pad you can also take the opportunity to press harder helping to level the shellac.
This is similar to stiffing but here you never add shellac.
Only alcohol.

French polishing is always a balance between shellac, oil, alcohol, light pressure and heavy pressure.
This is why french polishing is so tricky.
If any of these elements are out of balance things won’t go well.
You have to keep track of all of them.
I have decades of experience and can go months when everything is easy and then one day it all goes to $#!t.

To much of one thing or to little of the other and who knows what’s what.
At this point I just start over again by cleaning my pad and reloading it.
After reloading let it dry out for two days in a glass jar with the lit slightly open and it should be ready to go again - for the next bodying session.

Hope that helps.

Tom skips traditional "stiffening" or "spiriting" (I always thought of that as one step) by doing a final sand and polish using modern materials. Nothing wrong with that, just not 100% traditional.

I am a recent convert to this venerable art. I have never built more than 4 guitars in a year. If I build a dozen or more a year someday spraying some kind of UV cured or catalyzed finish would probably become a necessity. For now, the time spent French Polishing is comparable to what I spend fixing runs, Orange peel, sand throughs, working through the grits, etc. But the process is way more enjoyable, far less toxic, and so far much more consistent. Why we jump over FP and go straight to spray finishing when we start building is a mystery to me.


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... I'm working hard to rub them out as I see them while applying finish and that mostly works but at the same time I'm apparently also creating new defects. I guess this is what's hard about french polish...

Are the stiffing and spiriting steps done only once at the end of all the bodying sessions or are those techniques used after each session in the later stages of the finish?

When French polishing the best thing to do when you see a defect in process is to NOT "work hard to rub them out as you see them". For the most part ignore them and do not give them extra effort. If anything stop and give them less effort and or let the finish relax for a few hours or over night. If you focus on a dull area you tend to remove finish not add it. I am not sure what you consider a defect but a dull area or oil during the bodying sessions is normal. Just keep up with a consistent application.

In terms of stiffing and spirting off there are no rules about how often or when you do it. At any time in FP you can go back to any step including pumice fill and work your way back through finishing. At the end of a spirting off session or two if I am not happy I will go back and go through a few bodying sessions. For terminology set, I use a charge of the muneca to define a session.