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Crosshatch Adhesion Tests on Tile

By Jack Josephsen

Here's a quick video on adhesion to tiles and how to do a simple test to gauge if you can get a good bond.

If you're wondering why I didn't grind the tile first, it's because the client actually liked the look/pattern of the tile and was hoping that could be preserved if possible. By simply going over the top with a clear coat, he could get the extra slip resistance he was looking for without ruining the look.  

Video Transcription:

So here today, I wanted to just run through a little quick test. We get asked to overcoat tiles all the time in our industry, and the common problem is we don't really know whether we're going to stick to it or not.

We talk about grinding off the surface and opening it up and then having a porous tile that we can then stick to. All of that it's good in theory, but it doesn't always work that way.

So sometimes we have to see whether we can actually get adhesion to a tile and it will vary from tile to tile. So certainly I'm cautious about the idea of saying you can stick to tiles with epoxy, but in this case here, it's a non-slip tile. It doesn't appear porous. The tile itself, and when you look at the back of it, if you can get to the back of it, you can see that it's monolithic throughout, like homogeneous design throughout.

So I'm doubtful it's going to have any porosity to it, but I'm wondering whether we can get some kind of mechanical bond to it. The client in this case, had a tile that we could have a play with and determine without doing it on the site itself. So what I'm going to do today... Ideally we are doing proper tensile pull off tests, but you don't always have time for that. So today we're just going to do a basic crosshatch test and that'll give us an indication of whether we're on the right track or not.

My guess is we're not on the right track, but at least this will prove it and it'll also show the client that we are taking on the proper approach in their best interest before we go and do their job.

So here we are, we've got two different types of products that we're going to test on this tile. This is an epoxy and that will be indicative of whether an epoxy will bind to it, which means that they could do a solid colour system or they can do flake systems and broadcast non-slip and different things like that.

The other coding over here is a solventless PU, so a 100% solids PU, direct to tile. We really only just cleaned the tile. We haven't abraded it and so forth, so it's a worst case scenario to see if we can get some mechanical adhesion.

The coatings are only about a hundred microns each, so it's not particularly thick and it will give us an indicator as soon as we've done the crosshatch, whether we've got adhesion or not. So there is a proper standard for doing a crosshatch test. In basic terms, we're just looking to do three scores approximately three millimeters apart both directions and then using tape is I think the official way.

You stick the tape down and pull it off to see whether it comes off. If it does, it's obviously not very good, but if it does stick, then I still like to prize at it and see how much effort it requires to come off. So let's do this thing and see what happens. Alright, so we got our scores in there off and ready as you can see, but it's certainly going to give us an indication.

I use cloth tape because the adhesion is much better than just basic masking tape. So rub it in well, and you can see there that it's pulled off. I don't know if you can see it. I will show you in a minute, but it's obviously pulled that off so I don't have a lot of faith in the PU sticking direct to tile. And let's have a go at the epoxy.

And there you can also see that it's pulling off the pieces there off the tile. So a quick test, but it is giving us a good indication that you couldn't just clean the tile and put your two coatings on.

As always, I'm Resin Jack.

Take care and keep smiling.

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