Mirror Tiles- Grout

[Mango5078]

Advice required please!
Covering a fiber glass sculpture in circular mirror mosaic tiles for an outdoor art trail. I was advised to use mirror adhesive to prevent mirror backing degrading and began applying tiles by individually applying adhesive tile by tile as the surface is uneven and some needed more adhesive to level out with the surrounding tiles....now I discover that the cement in grouts can degrade the mirror backing and some of the tiles that went on first aren't completely coated with adhesive. Are there any grouts/epoxy mixes that are less likely to affect the mirror backing (mercury coated) I have tried contacting two different grout manufacturers but getting mixed messages. As the sculpture needs also water/frost resistant grout and the joints are between 2-10mm because I'm using varying sized circular tiles. Any advice appreciated as I need to find the solution asap!
I have seen the acid resistant Epoxy grouts used by Mapei but due to joint widths they weren't advised and the Ultra colour was recommended though that's a grittier mixture and cement based I believe but doesn't cause efflorescence..I'm not sure which of these causes long term mirror backing degradation?
Had I known the grout risk I would have covered each tile back fully with adhesive as I have done with all subsequent tiles since I found this out.

 

[One Day]

Gisela Gibbon - Mosaics, Stone Carvings, Paintings This lady will advise. Drop her an email...

 

[Bill]

lime mortar?

 

[Mango5078]

Thanks both, Tom I'm not sure that Lime mortar wouldn't have the same problem as cement based grout and be too harsh for the mirror backing?
Impish, I contacted Gisela as you suggested and she has given me lots of information of helpful suggestions. It seems as though anything I try will be a risk and I'm going to be worrying that the mirrors are degrading after I've handed over the sculpture. It's very time consuming and expensive and I'm desperate to limit any potential damage from the grout...

 

[Old Mod]

You do appreciate @Mango5078
As payment for the above refferel, we require images of the finished item in question! 🙂

We like pretty pictures! 🙄

 

[White Room]

Thanks both, Tom I'm not sure that Lime mortar wouldn't have the same problem as cement based grout and be too harsh for the mirror backing?
Impish, I contacted Gisela as you suggested and she has given me lots of information of helpful suggestions. It seems as though anything I try will be a risk and I'm going to be worrying that the mirrors are degrading after I've handed over the sculpture. It's very time consuming and expensive and I'm desperate to limit any potential damage from the grout...

If lime mortar it has Hydraulic lime which burns like hell....