Preparing Floor for Ceramic Tile Installation

I removed the original floor in my Kitchen (a glued down square 12x12 tile floor) in preparation to install ceramic tile flooring. The house was built about 10 years ago on a concrete slab and this was the original floor. Once I pulled up the old tile floor, what remains is a very thin layer of sticky glue on the concrete (not enough to create a leveling problem).

My question is Can I lay the new ceramic tile floor on top of the concrete with this thin film of glue? Or do I need to do further preparation? The store I purchased the ceramic tile floor from seems to think that it is ok.

Thanks,

John

 

Place hot water on the glue, is it softens it up, keep scraping, if not, use a good modified thinset and go for it.

Any cracks or paint under that glue.