If you google "Bob Flexner French Polish" I'm sure his method will come up. I based my technique on what he wrote in his book Understanding Wood Finishing.
That has nothing to do with shellac over poly. The shellac over poly was simply me being frustrated with the stupid project and also wanting to try something new. I didn't want to sand off the poly and take it down to bare wood as I'd have to stain it again too. As I mentioned, this isn't fine furniture, it's construction grade 2x8's and a slab of BC oak plywood from the BORG. I didn't run anything through a planer or jointer so it's really not all that flat to begin with.
Sanding off the poly would've involved actually flattening the piece which would've taken a ton of time and also certainly worn through the face veneer of the plywood in a number of spots.
Flexner's French Polishing method is basically
1) Fill pores
2) Level surface
3) Load your pad using a combination of shellac and DNA
4) Lube the pad using mineral oil - this creates a long "vapor trail" as the DNA evaporates out from under the oil. Makes it very easy to see how/where you've worked and also keeps the pad moving easier as it dries
5) Eventually, he says to just add DNA... that the pad will have "enough" shellac that you just need to thin it and dribble it out.... at this point you're mostly burnishing and bringing up the gloss
Jeff Jewitt's method appears to be (based on that one webpage)
1) Fill pores
2) Load your pad with shellac
3) Apply a thin coat and wait for it to cure hard, then mechanically level
4) Repeat step 3 until happy (or crazy)
5) Mechanically polish and perfect the gloss
Basically, my mistake was in Flexner step 5. Perhaps I had too much oil so the pad was still moving well. I certainly had too much DNA. It seems that the pad was probably
pulling up shellac instead of
putting it down.
The second time around, I made three changes
- I re-arranged my lighting to give me a better view on what was going on. It seems that proper lighting is VERY important for this process. You can't just have "lots" of light, you need to have it in the proper locations so you can easily see the reflection in your work.
- I re-made my pad. The first one was a ball of t-shirt wrapped in more t-shirt. This time I used cotton balls wrapped in t-shirt. Next time, I'm definitely going for a large lump of cheese cloth for the core. The cotton balls just compressed and it seemed like the shellac didn't distribute evenly through them. Near the end, it seemed like more shellac was coming out via the edges/sides of the pad rather than the flat part touching the surface. Also, if I'm doing another 5'x3' desktop or table, I will make the pad bigger.
- I did not add shellac and DNA, I put shellac only into the pad. This meant I was a little more aggressive with re-filling the pad as it became stickier faster. I'm assuming I was thinning too much earlier. By not adding additional DNA, it ensured I had a 2-ish lb cut of shellac at all times. The oil then helped keep everything moving and the vapor trail was a big plus.
My natural tendencies lean towards "Too much is just enough" but this process is certainly "a little goes a long way" or perhaps "less is more".
It was very nice to be able to achieve a "good enough" finish in about 6 hrs of work (2x 1hr applications + 2x 2hr cure times) which would've taken me probably 2 days using wipe-on polyurethane. Heck, considering the problems I had with the poly on this project (dust, bugs, bubbles, etc) I might not use it again until I can get a spray booth setup.
Took this photo this morning after about 9 hrs of curing. Oil's been cleaned off, this is perfectly dry. Certainly not perfect, I'm happy enough that I'm skipping the planned wax-n-polish.