help please sticking manufactured stone to mortar bed!!!!

[tenax]

i am doing a fireplace including hearth using eldorado manufactured stone including for the hearth (20 x 20 eldorado stone on hearth. i made a mortar bed for the stone yeserday without issue, following manufacturers instructions to put down lath then a scratch coat and let it dry for 24 hours. today, i i mixed up the mortar mix that the hearth stones would bond to. i tried to put it on the stones first but it kept falling off that way so i applied it to the mortar bed instead ( i did not pre-wet the mortar bed or manufacture hearth stones. i have seen that tip on other companies instructions but didn't see it on eldorado's, soooo) i troweled the mortar, laid the stones, tamped them down a bit with a rubber mallet and went back to check on them 7 hours later. the stones were not adhering. so, i've just lifted them up and note that in a few spots on the stones the mortar stuck a bit, but for the most part it was sticking much better to the mortar bed but not so much that i couldn't pretty easily trowel the new mortar off the old. i do have a bonding agent i could have mixed with the mortar but i didn't bother as i thought i'd save it for the vertical surface stones, figuring between the hearth being horizontal and the weight of the stones, it would adhere just like that. the consistency of the mix i used was about like putty..not soupy or running at all..it was still moist when i pulled the stones but even as i was applying it, i thought it might be a bit too dry (started to get a bit chunky, quickly in a 22 degree celsius 30% humidity house.

was i simply too impatient in how quickly i thought it would set up? i don't think so given that if i had been applyiing it to the wall stones my expectation would have had to have been some adhesion within seconds. to grade the adhesion level i was experiencing with the hearth stones, i'd say it was a 1 on a scale of 1 out of 10, 8 hours after application.

help plse!

 

[John_M]

Tenax, I do not know the answer to your specific question about why the manufactured stone is not sticking to the mortar base. However, I can offer a suggestion based on my experience of having just four days ago laying porcelain tile on a bed of Latex Modified Thinset Mortar. The thinset mortar I used was specifically recommended for porcelain and ceramic tile. It was specifically NOT recommended for marble and other NATURAL stones.

The MANUFACTURED stone you are using might require an adhesive instead of a cement based mortar. Look closely at the instructions that came with your stone. See if it specifies an ADHESIVE or a mortar. If that does not help, go to a Lowes or a Home Depot if you have one in your area and check the tile section. There will be many bags and boxes of various mortars and adhesives. Each product is recommended for installing a specific kind of manufactured or natural stone or tile. Usually the instructions on the bag will tell you what the product should and should NOT be used for.

I hope you were able to remove all of the mortar which did not work. Boy, what a bummer!

The tile I installed five days ago is my very first tile job. I was as nervous as a bank robber during every step of the process. I was just as nervous doing the grouting yesterday. I am lucky; everything turned out okay. I am now spraying a very fine mist of water on the grout about every 3-4 hours to prolong the curing process. The misting will continue for 24 hours. It is intended to make the grout harder and more durable.

Good luck in your search for the right product for the manufactured stone.

John_M

 

[Dune]

Bonding agent, AND soaking the stone in a barrel of water.

 

[tenax]

type N or S mortar mix is what is recommended and what i have (type S is pretty standard i believe). otherwise, a few things i have thought to try:

a) use bonding agent
b) a bit thinner mix
c) only put a ring of mortar under each stone (maybe the biggest mistake i made, as i had coated the whole under surface below the stones so likely was not creating required suction effect?)

i wish this was a tile job i had no problem when i tiled my kitchen (my first tile project too and 7 years later it's still great)

 

[tenax]

Bonding agent, AND soaking the stone in a barrel of water.

seriously? i know i saw this on one application video for another product but..what do you mean by "soaking"?

 

[mjwendorf]

You didn't give your mud time to cure. Give it 24 hrs. Also if you want you can use a thin set to stick your stone, the biggest advantage to using a mud bed is you can put more mud under each stone for leveling.

 

[tenax]

thanks mj..i've mostly had success since the last post using the combo of water and the bonding agent, pre-wetting stones and a bit thinner mix. but you're right in that i hadn't let it sit for 24 hours but thought after 16 i'd have a fair degree of adhesion. i got almost instantly a much greater level of adhesion the 2nd time around using the tips above. i'm about a 3rd of the way up my wall and it's going pretty good..i've had a few "pesky" stones that i've had to remount for no good reason that i can figure, but ..my biggest concern at the moment seems to be how i'm going to clean the mortar smears that got on the stone off.

 

[tenax]

thanks to those who helped with advice..aside from cleanup and finishing the edges, my wall was completed today. i used a slighly more wet mix today and every stone stuck without issue. i love the bonding agent and think it made a huge difference!

 

[Hogwildz]

What bonding agent did you use?

 

[tenax]

i used a 1 to 1 mix of water and stone mason acryli bond. seemed to be easily available at a lot of places. it starts to set up within about 10 minutes after mixing so i had to add a touch more water to keep it pliable as i wanted.