Mosaic on polystyrene outdoors, without grout

[bygganders]

I have a hot tub supported by foam (pacific).
We want to cover parts of the foam with glass mosaic, without grouting.
Thinking of gluing the mosaic directly onto the foam.

Possible or completely wrong?

Does the surface need to be treated or primed first?

Grateful for any tips

Ander

 

[neo11]

Might possibly work, but why shouldn't you grout?
I don't think any preparatory work is needed.
At first, I thought about applying a thin layer of adhesive on the board for better adhesion.
But the mosaic is set with adhesive, so there shouldn't be any difference.
However, use outdoor adhesive, which is a given.
Over a month-old thread though, maybe you're done?

 

[bygganders]

Could work, but why not use grout?
I don't think any preparatory work is needed.
I first thought of applying a thin layer of adhesive on the board for better grip.
But the mosaic is set with adhesive, so there should be no difference.
But use adhesive for outdoor use, which is a given.
Over 1 month old thread though, maybe you're done?

No, the thread is only a few weeks old, and we are not done.

We will cover the foam with thin sheet metal.
Then glue the mosaic onto the metal.
Since the foam itself flexes a bit, if you kick the mosaic it will likely flex.
But with a fairly elastic adhesive, this movement should be fine...

But what about non-elastic grout with movement?
(We have found some elastic grout now after the thread was created)