Prefinishing the panels was a given due to the fact that they are a free floating trapped panel. If they’d been finished in place then humidity changes would have caused them to swell and shrink beyond the position they were assembled in and left me an ugly witness line. That wouldn’t do at all. Another consideration is the stink. Oil finishing leaves an aroma for weeks or months until the finish finally cures and all the solvent is gone. That isn’t such an issue on the outside but on the inside of a closed box that will greatly prolong the de-stinking and would impart a certain odour to any clothing items placed within. Oil sanding is also a very time consuming process and prefinishing both sides of the panels with oil would have taken a LONG time. I’m down to a month and a half before delivery so time isn’t exactly on my side.
The process, if you’re unfamiliar with oil sanding, is sand the wood from about 80 to 220 without missing a grit and ensuring that you’ve fully erased the sanding marks left from the grit before. Then you flood the piece with the oil and sand up a slurry using 220 grit paper, work the slurry into the pores, let stand 10 minutes and lightly buff it off. Wait 24 hours and evaluate the status of the pore filling, repeating as many times as it take to fill to your satisfaction. Then you repeat with 320, wait 24 hours, 400, wait, 600, wait, two non-sanded build coats with 24 hours between and then a 200 hour cure before final rub out. On both sides. Ugh. You can abbreviate the process if you want but when done correctly you will have a very baby butt smooth surface with a nice satin or semigloss sheen. And like a baby’s butt, it will stink for a while. Time drove me to a different procedure. The inside of the box surfaces were finished with shellac due to the visual similarity to the oil finish, the speed of curing, the similar sheen level and no stink. I was able to finish the backside of each panel and 24 hours later start the oil sanding process on the front. I probably should have sanded all my ash parts before I did the panels but I didn’t and, since my shop is small, I had to wait so that dust wouldn’t stick to the finish. My box spent nearly two weeks like this:
Although my wife was supportive of that location it was difficult to convince my cats to keep off the chair.
The panels certainly started to show off that sapele ribbon that I was looking for:
When the panels were finished I was able to sand all the ash parts and begin assembly of the box. First I assembled the front, waited 24 hours before assembling the back, then 24 hours later I put in the sides and bottom and had a box! The pictures are all taken with my cell phone in bad lighting so I’m sorry that they are slightly blurred. None of them really show off the ribbon but the reflection shows the sheen level I got with the antique oil.
The next two days was spent eliminating as many gaps as possible, mostly by gluing in very thin pieces of ash and avoiding wood filler where possible. Wood filler, not putty. Putty doesn’t tend to dry but wood filler does. I used the timbermate wood filler and was pleased with the ease of use but I should have opted for the ash tint vs the natural. It probably would have been better matched. Argh!
-- Mistake? No, that's just an unexpected design opportunity....