Once the process is completed you can enter the stage of a real craft.
Down from grit 80/100 to 220. No jumps over the individual grit sizes to avoid scratches.
Carving the groove
Few blisters is the lesser cost of this work. The chisels can do much more harm if they enter any soft tissue...
Carving the edges...
...to get rid of some excess material and/or to fine tune parts of the outer sides...
Staining or painting
Once you have finished the carving of the edges you can paint them. Also you can stain or paint the surface to enhance the structure of the wood.
OK, that is for the craft part. Now we need to change the hat to become a chemist.
First of all I must highlight the fact that this part can get extremely nasty if safety rules are not followed.
An acrylic resin is the magic to keep the board as flat as possible and to make it more resistant against forces of the Nature.
I use a mixture of Paraloid, but there are other brands for sure. For the penetration it is better to work with materials ( both wood and liquids ) that have a little bit higher temperature. It increases the depth of the penetration. It is not a good idea though to heat the Paraloid on your stove. It is a solution in some quite dangerous liquids such as toluene or xylene.. So I just use well heated water and place the can with Paraloid in the water bath. Also I would strongly recommend to work in well ventilated areas. Safety googles and gloves should be used.
Once the pieces of wood are soaked I wrap them in a stretch foil and fix them again between two pieces of plywood. Just to make clear with the plates: "I want you to keep this flat shape"
After 2/3 days I usually repeat the penetration once again.
There are a lot of videos about this subject - much more advanced methods can be used... But this simple one is OK. I have few plates that have been finished last year and they keep the shape without any distortion.
I will share more results later this week. Some of the plates will be for sale in the Offer page.