Slate going over old glue

tomke · September 4, 2009, 07:34 AM

I have a pretty similar issue. I'm tiling with 6x6 slate tiles in a 25 sqft 1/2 bathroom. I am the homeowner. I pulled up the carpet and as much of the padding as possible. There are still some areas with glue that must be 30 yrs old (house's age). I've looked into renting a grinder but no Lowes or HD in my area rent them. I wound up renting a vinyl floor removal tool, which helped some, but there are still some small areas of adhesive remaining. What I gather from these posts, is the consensus that its probably ok for me to thinset over whatever adhesive is left?

Its not a very big room
The tiles are pretty small
The slate is naturally uneven anyway

Thoughts/Suggestions?!

Bill Watson · September 4, 2009, 01:06 PM

tomke said

I have a pretty similar issue. I'm tiling with 6x6 slate tiles in a 25 sqft 1/2 bathroom. I am the homeowner. I pulled up the carpet and as much of the padding as possible. There are still some areas with glue that must be 30 yrs old (house's age). I've looked into renting a grinder but no Lowes or HD in my area rent them. I wound up renting a vinyl floor removal tool, which helped some, but there are still some small areas of adhesive remaining. What I gather from these posts, is the consensus that its probably ok for me to thinset over whatever adhesive is left?

Its not a very big room
The tiles are pretty small
The slate is naturally uneven anyway

Thoughts/Suggestions?!

Several questions spring to mind:
1. Is this a concrete substrate you are going over? If the substrate is wood, you should probably consider using a tile backer.
2. Is ALL of the carpet padding gone?
3. Was there exisiting vinyl as well? Knowing this may help determine what sort of adhesive is remaining. Or, if the remaining adhesive is "pad glue", it usually can be scraped down to a film. Generally, it is best to remove all adhesive from the surface.
4. What sort of a "vinyl floor removal tool" did you wind up renting? Most often, especially if the substrate is concrete, a 4" razor scraper works very well for removing remaining adhesive in a small area such as yours. Cheap, and available at your local big box store.
5. Have you been able to check for flatness of your substrate yet? Even with small tiles it needs to be as flat as you can possibly get it.

Let's start with these questions and go from there.

tomke · September 4, 2009, 01:25 PM

There is no wood, this is the foundation. There was no vinyl floor either, the scraper I rented was the closest thing I could find to a carpet scraper. It was basically a 4" blade that vibrated mechanically. I'm currently trying to use a WW Henry adhesive remover to get whats left. Seems to be going OK.
All the padding is up, the only thing left is a very small bit which is basically adhered to the glue.
As far as I could tell (prior to demo of cabinet and toilet) the floor was pretty level, buts its hard to tell with patches of adhesive.

What would you suggest after the chemical treatment?

Barry Carlton · September 4, 2009, 01:32 PM

I may be over ridden here, but I would immediatley stop the chemical removal!!!!

b

Kman · September 4, 2009, 02:26 PM

No, Barry, you're right. Any chemical you put on there is a likely to be a bond-breaker with the thinset.

You need a razor scraper to get that old glue off. They are at Lowe's Tile Solutions at Lowe's: 4" Adjustable Floor and Wall Scraper and they can go through most adhesives fairly quickly.

Check the chemical adhesive remover you're using now and see what they recommend for cleaning up afterward. You need to get as much of that off the slab as possible.

tomke · September 4, 2009, 02:42 PM

Got it.

The adhesive remover is mixed 1 part to 4 parts water. According to the bottle, it can be used on concrete and washed thoroughly with water. I am using the razor scraper.

So I get up as much as possible, wash it, let the floor dry, then thin set?

Kman · September 4, 2009, 02:58 PM

Can you give us a product number or a link to the product that you are using to remove the glue?

Barry Carlton · September 4, 2009, 03:04 PM

Kman said

Can you give us a product number or a link to the product that you are using to remove the glue?

I hate to presume, but I would almost bet that this is what is being used: W.W. Henry Flooring Adhesives - Product Listing

b

tomke · September 4, 2009, 03:06 PM

You presume correctly

Kman · September 4, 2009, 03:28 PM

Sounds like some pretty potent stuff.

http://www.wwhenry.com/assets/Produc...2012-22-08.pdf

I would call their tech support and tell them what you are doing and ask them what you can do to get that off the floor, whether it be washing it, grinding it, or whatever. I'm thinking that washing it a couple of times may work, but check with them just to be safe.
1-866-443-4455 or
724-203-5000

I assume you're doing a relatively small area, but you don't want to have to do it twice if there's a chance that the thinset will de-bond from the slab.

Bill Watson · September 4, 2009, 05:33 PM

Kman said

No, Barry, you're right. Any chemical you put on there is a likely to be a bond-breaker with the thinset.

You need a razor scraper to get that old glue off. They are at Lowe's Tile Solutions at Lowe's: 4" Adjustable Floor and Wall Scraper and they can go through most adhesives fairly quickly.

Check the chemical adhesive remover you're using now and see what they recommend for cleaning up afterward. You need to get as much of that off the slab as possible.

Please do listen to this!
Most chemical adhesive removers will act as a bond breaker, and you will not get a good mechanical or chemical bond with the new thinset.
Unfortunately, the best method is good old fashioned "grunt work" with a razor scraper.

At least it's a small area.

Jim McClain · September 4, 2009, 06:08 PM

Bill Watson said

... good old fashioned "grunt work" with a razor scraper.

It is amazing the number of people that buy these things and don't know the blades are in backwards for display and safety. Loosen the screws, flip the blade so the sharp edge is out and tighten the screws back up. Works better that way.

Jim

Floorguy · September 4, 2009, 07:54 PM

Jim McClain said

It is amazing the number of people that buy these things and don't know the blades are in backwards for display and safety. Loosen the screws, flip the blade so the sharp edge is out and tighten the screws back up. Works better that way.

Jim

That's too funny and so true!!

Got a call to do floor prep for a DIY'er. Go over to give them a bid and they are telling me how they tried and tried to scrape the slab, and showed me the scraper. The blade still in backwards. The little oval hole showing. Take out my screw driver and flip the blade and it works like a charm. I got $75 service call for showing them how to work a scraper.

tomke · September 5, 2009, 05:14 PM

Oh, no. Haha the blades were correct. The solvent did help, despite the dissenting opinion. That glue was like scraping wood!

Barry Carlton · September 5, 2009, 05:22 PM

tomke said

Oh, no. Haha the blades were correct. The solvent did help, despite the dissenting opinion. That glue was like scraping wood!

Those were not dissenting opinions. We all probably agree that the solvent makes it easier to remove the old adhesive, (without a doubt, I agree that it does). The problem that voids most warranties for the new adhesives being used, is that wood and concrete is porous and absorbs a portion of the solvent, the solvent, turn continues to do it's job and breaks down the new adhesives to the point of an adhesion failure. This is why most adhesive and flooring manufacturers will not warrant their products over a substrate that has had an adhesive removal solution applied.

b