Slate bathTUB?? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Dan Heller
03-10-2004, 10:50 PM
We're either brilliant craftsman, or the dumbest guys in the world. I'm worried we may be the latter...We've spent ungodly amounts of time creating a beautiful looking natural slate shower AND bathtub. It's about 5' x 3.5'. The spillover drain in this enclosure is 18" high. PROBLEM: We assumed an extra heavy duty stone sealer could also make this creation WATERPROOF, i.e hold water like a regular tub. Unfortunately, all the manufacturers of the sealers do not recommend their products for that use. Fortunaely we first put a PVC liner in, then poured a slab for the bottom of the tub, then layed the tile. We're not worried about it leaking through the sub-floor, only that after a few long baths, slate will start to flake up. Can anyone help with this? The project is on hold as we research this issue trying to discover if this can be solved....Anyone with knowledge and experience in this area, please help!

Eternally Grateful,


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John Bridge
03-11-2004, 07:10 AM
Hi Dan, :)

I think the stone experts around here will need to know what type of stone was used. Also, does the liner go all the way up your "spill over"?

03-11-2004, 07:40 AM
Hi Dan :)

What is the name of your slate and where did it come from?

Shower walls are one thing, but is your tub actually tiled with slate, as well? Are you trying to make a slate tub hold water?

Got any pictures? :D

There are ways to reduce (Im not going to say eliminate) the flaking on some slates. What Im really concerned about is the slate turning to mush, eventually.

03-11-2004, 09:02 AM
The stone itself is key. I have seen 70 year old sinks made of black New England slate still going strong, but there are other slates that would never survive this application.
I'm betting it's gorgeous, though.
Good luck, Fern

Dan Heller
03-12-2004, 09:32 AM
Thank you to John, Tim and Fern for the fast reply!

I think the tile is Chinese. It's that multi colored (black, grey, red, rust, mustard and various shades therein.) A few tiles are rather powdery when flaked, others are very hard. Go to

and see the bottom pix of "Chinese Multi Colored Mix". That's the stuff. I can get an actual picture of the tub by tomorrow morning.

The PVC liner underneath goes up TO the spillover which is an 18", horizonatal design. Our intention was to have the tub actually HOLD water like a normal bathtub after many (MANY!)coats of a heavy duty sealant. I'm guessing we're probably in trouble based on the type of tile we used. The good news is, I mainly take showers, baths only a few times per year. Is this really good news? Or will the whole thing fail after a few baths?

THANK YOU! Please let me know if you have any other questions.

John Bridge
03-12-2004, 07:56 PM
No other questions, Dan. Most of the Chinese slate products are really soft. Absolutely not the kind of material I would consder using in a shower. :)

Rock polisher
03-17-2004, 05:45 PM
Tim hit the nail on the head, the slate will eventually turned to mush, its called lime putty. Tear it out after you take a picture. Sorry:(

Steven Hauser
03-17-2004, 05:55 PM
Hi Dan,

Yep, what Jeff said with out a coating.:(

The question is whether or not Tim would recommend an epoxy coating over the whole thing.

He also has some other pretty cool tricks as well.:D

Dan Heller
03-21-2004, 09:25 AM
Thanks for all the comments....

I've recently seen bathtubs made of concrete, a very pourous material and think the sealant used for that may work. I'll investigate. In the meantime, Tim, would you, as Steven suggested, reccomend an epoxy? We have to give it a try to at least see if it works before tearing it out.

In the end, if we do have to tear it out, it would just be the bottom "tub" part, right? The walls should still be fine with a sealant? Is that correct, Rock Polisher?


John Bridge
03-21-2004, 02:38 PM
I don't know, Dan. The best you can do is seal the heck out of it and hope for the best. Dry the shower after each use. :)

03-22-2004, 04:03 AM
This site elaborates on the hardness of chinese slate:

These guys quarry the stuff and do not appear to recommend using it in the manner you have chosen:

And these guys claim to have a sealer that works:

I must however agree with everyone here. You have made a beautiful mistake.

03-22-2004, 06:01 PM

Re. the epoxy thing: First of all I don't want to dampen your spirits because I like your "lets see if we can make this work attitude". But if you decide to go the epoxy route here's a few things to mull over...just food for thought.

I'm fairly sure that when Steven suggested running this epoxy idea by Tim (Tim hasn't showed up yet), he (Steven) was thinking both sides and bottom of the tub. But he can clarify all that for you. For this post I'm going to assume both, sides and bottom.

First of all, with epoxy you will significantly enhance your inability of ever removing that slate if it finally comes down to that.

Secondly, I've worked with epoxy (West System has a good line) quite a bit over the years and there are relatively few substances known to mankind that are more difficult to work with on vertical surfaces than epoxy. It's got the runs. ;)

The only way I know of to approach this problem is by using one of two methods. (a) Adding a base layer of tooling fiberglass cloth, then coating that with epoxy resin. The cloth turns transparent so that's not a problem. The cloth give the resin something to cling too so runoff is controllable. But because of the uneven slate surfaces, grout lines, etc. you most likely have with that tub, you will run into air entrapment issues using cloth. Those you can see and there not pretty.

(b) The only other method I know of to deal with this runny mess is by adding a thickening agent to the resin. And quite frankly, I've never seen an epoxy thickening agent that is transparent. They may exist, I've just never seen em. I supposed fumed silica would be worth a try which I have used with gel coat but not epoxy.

So those are some epoxy issues to think about. If you still really want to try to save that slate tub coating it with epoxy, get yourself a box, line that box with slate (leftovers), bottom and sides just like the tub, grout it then experiment.


Rock polisher
03-22-2004, 07:04 PM
I agree with John Dan, there arent any guarntees. Personally I think you have a better chance of winning big in vegas. Try taking a scrubby pad and wet the slate and scrub it. If it chalks off without to much abrasion than your only delaying the inevitable. As long as water can get to it , a problem will eventually arise

03-22-2004, 08:13 PM
I have installed Chinese slate, some is surprisingly hard and others soft. I haven't installed any as soft as Indian slate, it'll turn to mud in a bath tub.

03-23-2004, 06:18 AM
Dan,a little off topic but,what did you use for a drain?This question arises around here from time to time and it would be great if you could post a link or a product line for us.Thanks

03-23-2004, 09:27 AM

The slate is installed already, correct?

So we cant seal all sides of the tile.

The ONLY thing I can think of is a clear, chlorinated rubber, swimming pool paint. It will enhance the stone a bit, but most importantly, its a flexible product. Itll give and take with any movement. Epoxy is too rigid. WHEN a crack develops, water will find its way into the stone, but it will not find its way out.

Yepthis is what Id do if it were my slate tub. Id be sure to coat every area that water touches. ;)

Steven Hauser
03-23-2004, 09:54 AM

Thanks Tim.:D

Dan Heller
03-25-2004, 10:05 PM
All of your input and ideas are extremely helpful and appreciated!
Thank you!

We'll put 5 coats of acrylic in the tub area then fill it with water & test. I'll post the results. If it starts to fail, we'll try fiberglasss resin...

The drain is a standard shower drain from Home Depot. Not sure of the brand, not sure if I answered your question.


03-26-2004, 09:14 AM
Good luck Dan. I also think Tim's suggestion is your best bet.

However: If it starts to fail, we'll try fiberglasss resin...

Negatory fiberglass resin, either vinylester or polyester will be an option (compatibility issues) after you coat that slate with the swimming pool paint.

08-02-2006, 12:12 PM
Is there any way to do this properly? I have an old bath tub that I wanted to cover with slate, inside and out. Is there any slate and sealer that would work for this project?

If not, is there any kind of stone I could use for this project?



08-02-2006, 05:08 PM
Michelle, your bathtub is already waterproof, so adding tile to it is more of a problem getting it to lay on the curves and making the drain and overflow seal properly.

08-03-2006, 09:05 AM
I believe in a response above, someone said that the tile would disolve if not sealed and suggested using a pool sealer? That was really what I was worried about, keeping the tile intact. Would a pool sealer work?


08-03-2006, 12:03 PM
No, a sealer won't keep a stone together if it wants to dissolve or flake. Pick a good type of stone, and you won't have these problems.

08-03-2006, 12:10 PM
What is a good type of stone and a good sealer.


08-03-2006, 12:15 PM
Vermont slate will be good. It's dense so water won't soak in. Granite is also good.

I dunno about sealers.

08-03-2006, 04:56 PM
Okay. Is there any slate or other stone that I can use that I could buy at Home Depot or Lowes hopefully on one of their clearance pallets. Sorry to be such a pain. I really want to do this but I don't think I can afford specialized tile. I am looking at tile under $2 a square foot.


08-04-2006, 12:44 PM
Under $2 a square foot for natural stone you say? Well you will most likely get what you pay for. I'd spring for "slate look" ceramic and the hassles that come with cheap slate will more than be offset by ceramic tile. To do curves like I think you're looking to do you would need tile that is 2" square or even smaller. This will come in the form of mosaic sheets and no way you will find that for anywhere near $2 a square foot. Look to spend $12 and more a sf for mosiac and thats cheap. It sounds like you want to tile INSIDE your tub?? You would probably be better off taking out the tub and doing a shower, still is not going to be cheap. Probably best solution for you is waiting until you can afford to do the job properly. My .02 for what its worth.