Laying Slate [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile

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bsmothers56
08-29-2001, 05:23 PM
Mr Bridge answered a ? for me concerning laying slate. He said I could lay it over existing ceramic tile using a polymer thin set. I have the following questions concerning the slate itself.
1) Is there anything I need to wipe the backs with prior to laying it?

2) Do you lay it just like ceramic tile or is there some other method?

3) What depth of trowel should I use?

4) Are there any restrictions where this should not be laid (around water, etc)?

5) I read not to use a spreader when you grout but use a trowel, what is your suggestion?

Thanks for your help. I really appreciate it,
Brian
>

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Ron
08-29-2001, 11:45 PM
Brian,
Laying slate is a little bit trickier to do than ceramic tile.First of all,you can't score and snap it ,you have to wet-cut them.

Is it a fine calibrated slate like New England slate?Is it 12" or 16"?Rough Chinese,Indian?Does it look like select stuff or really randomly picked and unsquare?Polished,honed or rough?

I am assuming it is a popular product,probably 12" and fairly rough and uneven.

If so,here's how I approach thi type of slate:

1. Remove the cartons from the tiles and stack them in piles.
2.After you prepare a few layout lines,line up a row of tiles in a pleasing distribution of varying colours and textures.If some are cupped concavely or convexly(are those words in the dictionary or am I being a bit of a wordsmith?)or flat,try to keep these adjacent so that you don't get excessive lippage(edges sticking up from tile to tile).
3.Precut the tiles with which you are starting.I use a dry-cut blade on the wet-saw(better cooling to prevent layers of slate separating).Don't cut them dry,if possible.I then clean the sludge off the back with sponge and wipe with rag.Before I install,I sweep the dust off the back.Before laying check to see if there are any cracks or crumbly corners,save these for cuts.
4.You can use a premium modified thin-set mortar.I use either a 1/2" square notch or 3/4" half moon notch trowel if the tile are really irregular in thickness.Trowel out a nice even bed with the ribs of mortar ending up in one direction.Start with a thicker,flatter tile and set firmly in the bed making sure you get full coverage(slate is weak).The adjacent tile can be thinner but backbutter where necessary.Take a small pointy trowel(such as a 5"x2" pointy margin trowel)and run along the side of the tile forcing the mortar,that has squeezed up,against the bottom edge of tile and away from top edge of tile to keep things neat and mortar bed even.Can also use this trowel to apply extra mortar where necessary,on the bed or the back of the tile.Remember,full coverage is important.Try to avoid lippage and excessively large joints.I think a 3/16" joint is nice but with slate they can vary from 1/8 to 1/4" due to the irregular sizing.Don't hesitate to remove a really unsquare or overly large tile(in relation to the ones already installed)and fit another tile.Apparently in China and India they have some underpaid peasants cutting and selecting these slates under decidedly archaic conditions.Backbuttering can't be avoided here for a nice result.

Clean the mortar out of the joints and off the tile as you go using pointy trowel and sponge.Also,scrape off any flaky bits while handling the tiles.
5.After mortar is dry,I use a deck brush and clean water then a sponge or a sponge mop.Let all the water evaporate out of the installation.If using an invisible impregnator,colour enhancing matte or gloss sealer I use a synthetic lamb's wool pad to apply sealer.At least one coat before grouting.Should have at least 2 coats when job is finished.Don't skimp on the sealer ,buy a high quality product and follow safety precautions.

Nobody is familiar with the sealer I normally use,comes from NYC and is made in Carribean.Yes,there's something in it that makes me high.Rather drink Guinness though.

Also,my grouting techniques are a little different.But if your slate is really rough you may have to use a grouting bag and a bricklayer's joint smoothing tool(or a pastry bag and a copper tube...)

The other guys here will probably have other techniques,maybe I can learn also.These methods work for me except I grout all slates with a special grout clean-up bucket and sponge from Europe without leaving a haze.You may have to go the bag route to avoid a haze.Believe me,you don't want to end up with a stubborn haze on rough slate.

I always look forward to slate jobs.A real sense of pride comes with slate installations and I think the look is timeless in certain applications.Looks great adjacent to hardwoods.

Good luck.

bsmothers56
08-30-2001, 06:03 AM
Ron,
I appreciate the fast reply and you answered all my ?'s. The slate was made in China. It is stacked on a pallet so I haven't broke it out yet but the pieces I have looked at seem fairly square and flat. They are 12" squares. If this information provides answers for anymore advice please send it. This is the first time I will try to lay this and I want it to look nice and not like a novice did the job. Again I thank you for your help and have a great day, Brian

John Bridge
08-30-2001, 06:18 AM
Brian,

Ron did a great job. I'll only add that I like the sealers from Aquamix (just in case you can't find the one from the Carribean).

http://www.aquamix.com

Rob Z
08-30-2001, 07:40 AM
Thank you , Ron.

Brian, enjoy your project.

IBEW716
12-20-2004, 08:26 PM
My wife and I are about to tile a bedroom in chineese slate tile bought from the HD. I was totally amazed when I came home to find out the answers to many of my questions already. One set of answer howevers that I have not seen the answers to yet are these.....

Can you go from a gloss to a natural and vice versa? We are looking for a natural finish to the final product. What type of sealer should we use? Also can we change the finish later if we decide we'd prefer a gloss finish?

John Bridge
12-21-2004, 03:46 PM
Hello IB. :) Please give us a first name.

For a natural look you would use a Sealer like Impregnator Pro http://tileyourworld.com/catalog

Yes, you could move up to a gloss finish later. It's a little tougher the other way around. ;)

After you've replied, we'll split this off and make your own thread.

IBEW716
12-21-2004, 07:00 PM
My name is Steve Howell We live in Katy just inside the boundary at Fry Road just south of Clay. I am a electrician not a home builder but have found myself updating each room in my house currently on a two at a time basis. (I know bad idea!.....but I couldn't help myself.)

One other thing I should have asked last night has to do with the grout lines. What is the smallest I can get away with when using 61X16 slate tiles? If smaller than 1/4" can I still use sanded grout or should I go with an unsanded?

Dave the Tile Guy
12-21-2004, 07:21 PM
Hi Steve...

Im a journeyman tile setter and I lay a TON of slate..both guaged and unguaged. That Chinese slate you got from Home Depot will be a semi-gauged. Dont try to make your joints too tight....1/4 is the smallest you want to go...3/8 would be better....the reason is if your joint is too tight...you will have differences in heights from one tile to the next...if they're too close to each other you wont be able so "smooth" the differences with your grout joint.....imagine if you butt-jointed them...there would be sharp edges everywhere. with no room for transition. and definately do NOT used non-sanded grout...Sanded all the way. For sealer I use a product called Mira-shine. One coat will give it a unglazed wet look...two coats will give it a semi-satin finish....putting 3 or more and you can make it look like varnish... it will wear off after about 6 months or so depending on foot traffic....then you can just add another coat and bring up your desired finish. It goes on easy...just apply it with a sponge...wont leave residue marks and is fairly cheap. Hope this helps. Make sure you use a heavy notched trowel....1/2 inch minimum.

IBEW716
12-21-2004, 09:36 PM
Thank you Dave. I havn't been able to log on for several hours but thank you none the less.

Should these tiles be sealed prior to grouting as others have said, or can it be done later? What will happen if I don't seal them prior to grouting? Will I ever be able to get the grout haze off of them?

juwd194
05-17-2005, 11:13 AM
ROn- I have read some of your entries, and you really seem to know what you are talking about so I was hoping you could help me. I am an American living in London, and we just had our kitchen done, and installed black/gray natural slate tiles on the floor. Due to all the construction that was done after the slate was down, and carelessness by the builders, a lot of the slates either look "hazy", dull in color, or just seems to have specs of grout on them that won't come off. I care less about the grout stains as I do about the dullness because I think I have to accept that the grout/construction stains won't come out? I thought they would be black, but they look a very dull gray. We did put 2-3 layers of HG impregnator on, and I don't mind some of the natual stains that the tiles have, but the floor just looks unclean. They look better when they are wet, and I bought a HG color enhancer that sort of mutes the stains, it does help, but they still aren't glossy, and look dull. I've noticed a few others have mentioned sealers like Aquamix, and mira-shine, and so I was wondering if you had any advice on (1) Cleaning the tiles, and more importantly (2) Which sealer with give a wet, glossy look? I am in England and have found stores here unhelpful, so am willing to by one overseas.

I also realize I haven't given you many specs on the tiles, but I could send you pictures and more information if you have time to respond, which I would really appreciate. My email is katiekrohn@hotmail.com

Thanks very much,
Katie

Brian,
Laying slate is a little bit trickier to do than ceramic tile.First of all,you can't score and snap it ,you have to wet-cut them.

Is it a fine calibrated slate like New England slate?Is it 12" or 16"?Rough Chinese,Indian?Does it look like select stuff or really randomly picked and unsquare?Polished,honed or rough?

I am assuming it is a popular product,probably 12" and fairly rough and uneven.

If so,here's how I approach thi type of slate:

1. Remove the cartons from the tiles and stack them in piles.
2.After you prepare a few layout lines,line up a row of tiles in a pleasing distribution of varying colours and textures.If some are cupped concavely or convexly(are those words in the dictionary or am I being a bit of a wordsmith?)or flat,try to keep these adjacent so that you don't get excessive lippage(edges sticking up from tile to tile).
3.Precut the tiles with which you are starting.I use a dry-cut blade on the wet-saw(better cooling to prevent layers of slate separating).Don't cut them dry,if possible.I then clean the sludge off the back with sponge and wipe with rag.Before I install,I sweep the dust off the back.Before laying check to see if there are any cracks or crumbly corners,save these for cuts.
4.You can use a premium modified thin-set mortar.I use either a 1/2" square notch or 3/4" half moon notch trowel if the tile are really irregular in thickness.Trowel out a nice even bed with the ribs of mortar ending up in one direction.Start with a thicker,flatter tile and set firmly in the bed making sure you get full coverage(slate is weak).The adjacent tile can be thinner but backbutter where necessary.Take a small pointy trowel(such as a 5"x2" pointy margin trowel)and run along the side of the tile forcing the mortar,that has squeezed up,against the bottom edge of tile and away from top edge of tile to keep things neat and mortar bed even.Can also use this trowel to apply extra mortar where necessary,on the bed or the back of the tile.Remember,full coverage is important.Try to avoid lippage and excessively large joints.I think a 3/16" joint is nice but with slate they can vary from 1/8 to 1/4" due to the irregular sizing.Don't hesitate to remove a really unsquare or overly large tile(in relation to the ones already installed)and fit another tile.Apparently in China and India they have some underpaid peasants cutting and selecting these slates under decidedly archaic conditions.Backbuttering can't be avoided here for a nice result.

Clean the mortar out of the joints and off the tile as you go using pointy trowel and sponge.Also,scrape off any flaky bits while handling the tiles.
5.After mortar is dry,I use a deck brush and clean water then a sponge or a sponge mop.Let all the water evaporate out of the installation.If using an invisible impregnator,colour enhancing matte or gloss sealer I use a synthetic lamb's wool pad to apply sealer.At least one coat before grouting.Should have at least 2 coats when job is finished.Don't skimp on the sealer ,buy a high quality product and follow safety precautions.

Nobody is familiar with the sealer I normally use,comes from NYC and is made in Carribean.Yes,there's something in it that makes me high.Rather drink Guinness though.

Also,my grouting techniques are a little different.But if your slate is really rough you may have to use a grouting bag and a bricklayer's joint smoothing tool(or a pastry bag and a copper tube...)

The other guys here will probably have other techniques,maybe I can learn also.These methods work for me except I grout all slates with a special grout clean-up bucket and sponge from Europe without leaving a haze.You may have to go the bag route to avoid a haze.Believe me,you don't want to end up with a stubborn haze on rough slate.

I always look forward to slate jobs.A real sense of pride comes with slate installations and I think the look is timeless in certain applications.Looks great adjacent to hardwoods.

Good luck.