I wanted to add a short blog about the finishing process that I went through on the bottom of this piece. If you are not into finishing and related techniques, this would be a good place to stop.
It took me several tries to get the finish right on this piece. It is very different than finishing a salad bowl such as the one below in many respects but is similar in other ways.
For the preparation for the 5th coat, I buffed the slab with 0000 steel wool while it was spinning on the lathe. With the piece stationary I gave some extra buffing to a couple of sections that needed more attention and to the bark areas on the perimeter.
This time when I applied the finish I started in the center with the brush and worked towards the outside. I made a new cloth pad that was twice as big as my regular ones and more absorbent. I started from the inside and worked towards the outside. This worked very well and I got a great application.
I did take some video of this process but it needs editing and that is for another day.
P.S. Remember that you can click on any image to enlarge it.
The technique is the same but that is where the similarities end.
The first coat was applied after sanding to grit 400. This was pretty straight forward. The finish was allowed to be absorbed for a short time with the excess being wiped off with a cloth pad.
Normally, I buff with steel wool between coats. As this surface area was so large I decided to sand with grit 400. I did this on the lathe using my drill and sanding pads. This was a mistake as when the finish had dried I left new sanding lines behind.
After the second coat I sanded by hand with grit 600 and I did it with the piece off the lathe. I was able to see the holidays and excesses left by the previous coat and to remove them.
The next coat went on much better and with better results. I applied this finish by working in from the outside, re-charging my brush when it started to get dry. Then I started wiping back the finish with a cloth pad. I started in the center and worked my way to the outside. There problem was that the first finish applied had started to tack. The area in the middle of the piece looked great. The outside, not so good.
If it is not apparent, it should be noted that I do all my finishing on the lathe. I have more control over what I do and the finish can be put on and wiped back in a uniform manner.
When the finished dried this time I buffed the whole back with 0000 steel wool but again, I did it off the lathe. I was careful to look through the light and eliminate any anomalies. When I put the finish on this time I used a new can which has a longer tack time.
Again, I put the finish on from the outside towards the center and wiped back towards the outside. This worked quite well except that the pad overloaded with finish and was dripping on the floor. Fortunately, none of the drips landed back on the piece.
A Note About Dealing with the Irregular Edge
For the most part this piece looks round but it isn't. We tried to get the face plate in the rough center and succeeded quite well. However, when finishing out over the bark, the brush grabs and the pads catch on the sharp edges.
The technique that I finally arrived at to deal with this was to apply the finish with the brush to where it was just starting to cover the bark in some parts of the perimeter. Then when I was wiping back with the pad, I would hold it in such a way that the excess finish was being pushed towards the outer edge. When the pad got to about where I stopped using the brush I stopped the lathe and manually pushed the excess finish out onto the bark with the pad always working from the inside and towards the edge of the piece. This was very successful and eliminated any dripping.