<removed_4-10-13, 11:57.00>This message has been edited. Last edited by: Slayer,
If it's the Fast Set 90 that I am think of - the stuff used for drywall repair, then you are stuck with starting all over. Even though the Fast Set dry mix product is a lot more water resistant than regular drywall mud, it will still dissolve in water over time.
Save yourself all the grief that you'll get later and go ahead and remove everything - go back this thinset.
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