Printing an engraved block in a press requires a block that is consistently level and finding an end-grain block which is level and truly flat is not easy. Most blocks I purchase have low spots and sometimes the different segments of the block are at slightly different levels. This is a problem when printing on a press because the ink and the pressure are less in the low areas. I solve this problem by sanding all the blocks I use before doing any engraving on them. I've mounted plate glass to a high work table in my studio, upon which I attach carborundum sand paper in three grits (100 to 400) with rubber cement. For larger blocks I butt two sheets of the same grit together. The sand paper mounted tightly to the flat glass gives a very even surface.
I set the block on the sandpaper and, with modest pressure, I work the block in a small circular motion, moving it over the sand paper, making sure the block stays within the edges of the sandpaper. I try to keep the pressure I use evenly distributed over the back of the block. Periodically I rotate the block so I'm not applying more pressure to one area than another. At intervals I use a small hand vacuum to keep the grit of the sand paper from clogging with sand dust. Wood dust is easily removed this way. But "Resingrave" clogs the sand paper more and this synthetic material is very difficult to remove. I have found nearly all Resingrave blocks to have uneven surfaces. The Resingrave block surface has a smooth "skin" and, when sanded, small pits, which seem to be caused by air bubbles in the synthetic solution, are exposed.
I pick the block up every now and then and I look at the block at eye level, holding the block toward a strong light source. The pattern of sanded and unsanded portions of the block are apparent this way. When the entire surface texture of the block looks the same it means the high surfaces have been sanded down to match the low areas. I move then to the finer grit paper and repeat the process.
