Kiln Release Marks on Porcelain

[Higher Standard Tile]

Ever seen this before? Noticed after setting of course. At first it looks like just dust that would wipe off.

But the glaze is actually damaged. You can only see it when you look at it from an angle into the light. I'm assuming the manufacturer stacked the tiles before the glaze cured. The pattern in the glaze is the same as the back of the tile.

On a 1000 sqft job we found about 20 tiles. 10 off them are already set before we realized we had problem.

I've set some tile made in China that is of decent quality. This is not one of them.

[Tiger Mountain Tile Inc]

That's a bummer. Sorry.

[PetrH]

on the plus side, they look to be quite even in size. I've seen some chinese tile that was "rectified" to +/- 1/8"

[TonE]

Quality control in china. it's only 2 percent.
Consider yourself lucky.

[Floorit]

Isaac,

I had that same problem back in February. Also Chinese made, private labelled for a large tile co. The tile also had a shading issue on some that appeared to give them a striped appearance if you saw them in the right light reflection. Could not see either problem until after the tile was down and grouted. Not fun at all.

[ceramictec]

Isaac, have you tried some sulfamic acid to get the kiln slip off ?

[Higher Standard Tile]

The store I bought it from called the tile manufacturer rep and he recommended this acid cleaner-

Dupont Restore-

http://www2.dupont.com/Stone_Tech_Pr...c_cleaner.html

I don't have any yet, but tried Brian's suggestion with the Sulfamic Acid. It didn't seem to make a difference. May need to let it dwell longer. I mixed it pretty strong.

Also tried Aqua Mix Nano Scrub.- After scrubbing really hard it seemed to get better but not completely gone. May have to pull out the floor machine.

[Floorit]

Isaac & Brian,

On my issue, I used sulfamic acid, nano-scrub, blaze, vinegar, and glass cleaner, at various times, left them set anywhere from about a minute to an hour, used white scrub pads, clean cloths, sponges, etc. to no avail. I spent a ridiculous amount of time trying to resolve the issue. It's in the tile and it ain't coming out. It all had to be replaced.

[Arizona Floors]

I'm with Brian, it's kiln release (kiln slip- I haven't heard that term) that was transferred from the tile backs to the tile fronts during shipping and or storage.

The good, it can be removed without too much trouble.

The bad, I only know a restoration guy who can do it here. The most info he would give me was he used a combination of 3 things, whatever that meant. He makes a killing cleaning the tiles, the only other option is remove and replace.

Almost a year ago our local Emser Tile had a run of about 150,000 ft that was installed with that exact problem. Emser hired that restoration guy to clean the tiles.

Sorry, I know it's not helpful. But the manufacture should step up on this one especially if it comes down to replacement.

[ClaimsGuy]

Chances are strong that its kiln release.

If so, the tiles can be cleaned using a variety of solvents - I've seen some get cleaned with water, and others that require very strong acids. Common sense suggests that you start with the weakest stuff first.

The best method I've found so far uses a floor machine and a mild tile cleaner. If you don't have that machine available you can use acid or scrub it off with a nylon brush.

And yeah, we had to deal with a lot of this problem fairly recently, but found a permanent fix. Just put a sheet of paper between the tiles - its as simple as that.

Any other manufacturers reading this, take note!

[Arizona Floors]

Jeff, I wasn't throwing Emser under the buss, I didn't think about that when I posted.

It should be added, as far as I know, every job that had the kiln release issue was remedied by Emser immediately. And it's great that there are preventative measures now in place.

[ceramictec]

Originally Posted by Higher Standard Tile

The store I bought it from called the tile manufacturer rep and he recommended this acid cleaner-

if the sulfamic didn't work I can say the Restore wont do a thing. its not as strong.

Originally Posted by Arizona Floors

(kiln slip- I haven't heard that term)

calcined alumina-silicate engobe = clay slip, kiln slip, kiln release,
the ceramic rollers are sprayed with it to help the freshly fired tile "slip"
off them while they are still hot. that an the pattern on the bottom of the
tile that reduced the surface area that contacts the rollers.

[ceramictec]

Isaac,

I found this article that might help.

removing-kiln-release-marks-on-porcelain

[Higher Standard Tile]

Brian, I know you don't need any additional compliments but your web skills are pretty impressive, almost as good as your plank tile skills.

Thanks for tracking down that article. That is exactly the problem.

Interesting that I noticed the boxes did appear to have gotten wet at some point and the pallet was shrink wrapped holding in the moisture.

(When they added the thinset on the added extra shrink-wrap on top of the original.)

And if you look closely in the second picture you can see the roller marks.

I think this thread should be renamed- "Kiln Release Marks on Porcelain"

[Peerless Tile]

I know much wiser people than I have responded...but have you tried barkeepers friend....a bit abrasive and a bit acidic as well....a cheap try at it...