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johnc
02-27-2008, 06:20 PM
hi all, i was just reading a thread from a couple weeks ago about the so-called "pre-mixed thinset mortar" from Mapei. unfortunately i bought a bucket of it last week to do a shower surround. the guy at Lowe's sold it to me...i was reluctant and asked if it was a mastic and he told me, no - it's thinset mortar.

so like a question i read that was left unanswered in that old thread, i too used the stuff to "mortar" the joints in the hardibacker. I am not going to use in for setting the tile (i'll eat the $35), but can i use a true thinset mortar over that without too much worry? i'd really hate to tear that out and start over (and my wife would hate it more!)

thanks for the advice, i'm glad i found you, just wish it'd been a couple days earlier.

jc

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ceramictec
02-27-2008, 06:26 PM
if you already did your joints with the premixed, allow it to dry until it cures and gets hard.

did you mesh tape the joints ?

I would take the stuff back and say they sold you the wrong stuff and buy a $20 of good thin-set.

jadnashua
02-27-2008, 06:27 PM
You could probably get a stiff brush, get things really wet and brush it off; I know I got a similar thing off some wood after it had sat and hardened after a month or so.

It's often easier to do the joints as you tile, unlike drywall where you need to cover the tape and make it look pretty, if you do that with cbu, you'll end up with speed bumps, which makes it a pain to tile over.

Not sure the best approach. You might consider using some RedGard.

See what other thoughts you get...

John Bridge
02-27-2008, 06:28 PM
Welcome aboard, John. As you know, you're not the first innocent bystander to be bamboozled by the notorious "pre-mixed thin set" scam. ;)

ceramictec
02-27-2008, 06:30 PM
:sick:

johnc
02-27-2008, 06:44 PM
thanks all,

i did use mesh in the joints and just a couple days ago. i considered waiting to it all at once (tape joints and tile) but had a couple hours in the evening and figured i get a little done. it is a very thin coat as i have exp. with drywall and was wary of building a "lump".

so, should i wire brush it? what is the danger of going over it - that it isn't fully cured? i am definately going back and telling the Lowe's customer "service" what i think about this.

what product do (any/all) of you reccommend? is a polymer neccessary?

thanks again,
jc

ceramictec
02-27-2008, 07:08 PM
if its a very thin coat as you stated I don't think its a problem.
you will do more damage trying to remove it mess up the mesh and waste more money.

just use a good "powdered" thin set and you'll be fine.

Alto
02-27-2008, 07:20 PM
"i am definately going back and telling the Lowe's customer "service" what i think about this."

:lol1:

No offense intended, really, but if you find someone who knows what you are talking about, or cares, please post their name and address and we will nominate them for the Nobel Peace Prize (it's a lot easier to win than you might think).

Shop big box stores for price, not advice.

You could put one coat of Redgard on those joints and you'd be fine. You can usually find it at HD. :)

johnc
02-27-2008, 09:46 PM
the nice young lady at the returns counter didn't even blink, i told her it wasn't what i wanted, she asked if it was the wrong color, didn't notice the bucket had been opened and then gave the return credit. bless her heart.

i so use the local shops as much as possible. and walk away glad to have paid an extra 15$ for the advice i know i can trust.

redgard, eh? i'll check.

thanks for the help.

ceramictec
02-27-2008, 09:56 PM
yes, RedGard (http://www.custombuildingproducts.com/docs/data_sheets/RedGard%20DS%201_08.pdf?user=pro&lang=en) is good stuff.

you might be able to buy a small gallon size and waterproof all your walls before tiling.

:tup1:

johnc
02-27-2008, 09:59 PM
i picked up a bag of Mapei Ultraflex mortar when i returned the "pre-mix" (1/3 the cost!). is this a suitable mortar over the Redgard? or does it require a modified? if so, i'd love an brief explanation of the difference.

thanks.

ceramictec
02-27-2008, 10:23 PM
Ultraflex is a polymer-modified, thin-set mortar and is good to use over RedGard.

you can add the Keralastic liquid for even better performance.

johnc
02-28-2008, 12:08 PM
thanks for keeping me up to speed, ceramictec

right, Ultraflex is already modified, i think i knew that but the Lowe's guy confused me again when i asked about the Kerabond/Keralastic system.

i bought the Ultraflex 2, so i can mix it with the Keralastic liquid for better perfomance, or do you have to use the whole system, i.e. with the Kerabond powder? i am using 3x6 subways with a few rows of 1" glass squares.

having worked in the trades myself for many years, i do always want to use the best product, but i also don't need to go over my head.

HotinOKC
02-28-2008, 04:32 PM
No offense intended, really, but if you find someone who knows what you are talking about, or cares, please post their name and address and we will nominate them for the Nobel Peace Prize (it's a lot easier to win than you might think).

Ohhhhh...I might be in the running by myself. I'll take a gift certificate to Fridays, I don't need a trophy.... :lol1:

ceramictec
02-28-2008, 04:40 PM
the UltraFlex 2 is good as is.

this mortar has a high content of a unique dry polymer, resulting in excellent adhesion

for exterior commercial wall applications they recommend using the Kerabond / Keralastic.

Alto
02-28-2008, 06:30 PM
Mark,

Every rule has its exceptions, and you seem to be it. :clap1: I'll buy you a steak in Indy but you gotta come here to get it. :)

I actually know three guys at different big box locations that are completely and totally knowledgeable and professional. It makes life a lot easier.