Define what you mean by portland cement steel trowel finish, If
you literally mean you troweled on a slurry of Portland and water
on thinset, I don't see any way it could have worked. If all you
wanted was a slick cementitious finish, why didn't you hard trowel
the thinset? It would not have been my choice of products to
apply to the brick work. The finish coat you applied needed sand
and probably some lime to work. Cement alone is NOT a finish.
What do you want to end up with? I imagine it would be major to
try to remove the thinset. Can you remove all of your finish
coat, back down to the thinset? Is the thinset flat enough to be
finished or do you require additional "brown coat" type work? Is
there any physical tooth to your thinset coat, typically called a
"scratch coat" to provide adhesion of the next coat?
If you have a good plane established that will require no more
than an 1/8" for finish and you can get all of your finish off,
you may be able to apply EIFS finish coat. Most brands you will
not be able to buy, but you should be authorized to purchase
Parex, often available at major drywall houses. Here is some
info: http://www.parex.com/ click on Systems/EIFS
Keep the whole world singing . . . .
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