Flooring Tile - Black glue under asbestos tile

Does all of the black glue have to come up before mortor and tile are put down? If so, how do I get the glue up? Thanks.

Get as much off as you can. Try HOT water and a scraper. Some have added some dishwasher dertergent to the water to help but you need to flush real good so no soap residue remains, that residue can kill the bond of the thinset.
As far as thinset goes look for one rated to go over adhesive and cutback. You wont remove the stain from the concrete, thats ok.

Thanks for the reply. I'm tiling a bathroom with 6"x6" terra cotta look tile set 1/8" apart. How does this plan sound? Scrape and clean the concrete floor, use VersaBond thinset, sanded PolyBlend grout, and seal with Aquamix Gold 15.

If the grout joints are 1/8" or less use unsanded grout as it will pack into the narrow opening much better than the coarser sanded grout will. The rest sounds like a plan. :)

Thanks Bob. I was thinking sanded because I read somewhere that the sanded would look duller and look better with tile that was not shiny.

Another question about the grout. The tile I'm using has an uneven texture. I hadn't thought of this before, but the grout is going to be a real pain to get up completely, isn't it? Any suggestions? Thanks.

Some tile stores sell cleaners that have a grout release agent in them. If you cant find one, use SULFAMIC acid crystals sold at HD and other places. Mix with water and soak onto the tile to release any grout buildup.
When grouting dont do large areas so that the grout can dry hard to the tile. Use a sponge to clean the tile of most of the grout then use a scrub pad or a face cloth to work into the left behind grout in the textured surface. Dont use much water and be careful not to gouge the fresh, soft grout out of the joints. After that dries overnight, see whats left, then use the sulfamic crystals.