Where I get my epoxy and what I buy
First of all, I buy most of my epoxy from Noah's Marine. Info on Noah's can be found here (scroll down). Specific info on the resin can be found here. I use the medium hardener. I also use the pigments that Noah's provide. They can provide measuring accessories as accuracy is essential.
There are many epoxies
I have tried other epoxies but for the most part they have specific uses and are not applicable to my situations. Some are meant to cover artworks with thin clear coatings. Some are more UV stable than others. Some require higher room temperatures to work or set properly and thus need to be set in warm water baths.
(An update here. I had a problem with some of Noah's epoxies and that problem is detailed here. If the page asks for a password, please use 'noahs'. This is part of the experimenting that I did. The resulting piece was not very successful.)
I use wash coats to penetrate rotten or very soft woods to give them integrity for turning. On end grain a wash coat will go in up to 5/16" (8 mm). In soft wood such as spalted the depth can be anything from 1/8" to 3/16" (3 mm to 5 mm)
When I mix my epoxy it is 2 parts resin to 1 part hardener. To make a wash coat with the viscosity of water I add another 1 part of lacquer thinner. If a thicker coat more like a thin syrup is desired then I use less lacquer thinner. Stir the epoxy resin and hardener first then add the lacquer thinner.
Two cautions about the lacquer thinner
A mask is definitely needed when working with the stuff. It smells bad and can give headaches. I get migraines from it. When I am using it I make sure that the application is the last thing I do before I leave the studio for the day. My studio is in a separate building. This should not be done in a home workshop that is part of the house.
Secondly, the hardening of the epoxy takes considerably longer when using lacquer thinner. It can take from several days to more than a week. Lacquer thinner also weakens the epoxy. I don't use this technique for anything else.
Turning wood strengthened with a wash coat
When I am turning end grain such as that described in the previous posts, I only turn the epoxied wood until the wood starts to tear instead of cut. I find that using a very sharp gouge, the transition from the epoxied wood is readily apparent. At this point I stop and apply another wash coat. It takes much longer to turn a piece this way but the integrity of the wood is essential to the success of the piece.
Sanding and finishing after turning
After I have finished with the gouge and am ready to sand, I apply one last wash coat. This makes the turned surface hard enough to sand and will give the entire area to be sanded the same density. This is important as I do not want to introduce texture where none is desired.
I usually sand from Grit 60 to 1000. Going all the way to 1000 is not necessary unless there are large areas of clear epoxy to be sanded. The reason for going to 1000 is to completely removed the sanding lines. I am able to apply my finish over the epoxy but I try not to use more than 3 coats.
I hope this covers some of the questions that may have arisen in the previous posts. I will go into sanding and finishing in more detail in a future post.