On Jun 9, 8:13*pm, "The Henchman" wrote:
Concrete sub-floor, no backer board. *40 year old 4 x 3 tiles with yellow
"mastic" as the adhesive. * It's caked on good underneath and it's old. * *I
wanna prevent renting a Hilti/Kango with a scrapper cause it'll cost $100
around these parts for a day. *That'll be a last resort I guess

Solvents?

And type of manual scrapers?

grinders or some other abrasive?

I can't damage the sub-floor (concrete) underneath.

Even with the long bar you wont damage the concrete, chips dont count
as damage, and you'll not crack the slab, also concrete with mastic on
it is already "damaged".