If you want to use a one step method to save time, only use products that have been successfully tested with your tiles.
The so-called “one step method” is a simplification of the usual thinset/grouting procedure that involves using a mixed grout/thinset mixture and squeezing it through the back of the tiles to fill the spaces.
In fact the name of this method is a little misleading: once the job is dry, there is a second step. You will need to re-mix a small amount of the same thinset/grout material for touching up grout joints and imperfections. Nevertheless, this method does represent a time-saving departure from the traditional method of thinsetting, then grouting; what is more, it eliminates the problem of the look of dried thinset encroaching through a different colored grout.
Is The Method Supported By Your Tile’s Manufacturer?
There are several issues to consider if you wish to use this method. The first is – has the grout/thinset mixture been tested for this purpose? Will the tile manufacturer support this method? Glass tiles can be expensive, and seemingly extraneous steps can be a practical way of protecting your investment ( the use of crack isolation membranes are a good case in point).
Experience has shown that glass tile often comes loose from standard setting beds over time – it needs the extra grip afforded by a good quality, specified thinset. Standard thinset is too sticky to be used as grout and grout is probably not strong enough to be used as thinset. Will the two combined work? What if an additive is mixed in? Ask the tile manufacturer(s) – as different types of glass tiles have different setting requirements.
Tile adhesive and sealant specialist Mapei recommends their Keracrete liquid latex mixed with Keracolor U grout for one step applications of mosaics. Mapei has partnered with Italian company Bisazza Tile for many years and this is an approved method for them and some other manufacturers. Laticrete has suggested their Tri-Poly Fortified Sanded Grout (1500 Series) mixed with Laticrete 4237 Latex Thin-Set Mortar Additive.
Because glass tiles can vary in both thickness and some technical properties, make sure your manufacturer has approved the method for the tiles you are using.
When grout is mixed with a latex thinset additive, it becomes sticky and smears easily. It may also shrink once the latex dries, leaving spaces between the tiles.
One step methods are usuallychosen to quickly apply colored grout to a tile. In some cases, however, non-white grouts may adversely affect the look of the glass tile – particularly if a dark grout is used. Colors in the thinset/grout may be just enough to cause an undesirable shift in the final look of the tiles.
A Pro’s Alternative – One Step, Two Products
Seattle installer Tom Hulse, of Hulse Tile and Stone, offers an alternative. He uses two exclusive products, grout and thinset – but performs a one-time installation.
Tom uses one bucket of thinset, and one bucket of regular grout. On a trowelled, skimmed thinset bed, he lays face-mounted tile sheets that have been filled with grout from the back – backbuttered on using a grout float. The sheets are then turned over, put into place and lightly beaten in. Once 6- 9 square feet are completed and partially set up, Tom goes back, removes the plastic or wets and pulls the paper facing, and straighten the lines with an 8″ scraper blade.
For photos and more on Tom’s method, see this posting from the John Bridge Ceramic Tile forums.
An advantage of the two-step method is that it is precise and relatively easy to control. One-step methods trade off some time savings with additional complexity – and are usually employed only by seasoned professionals.
If the job fails, the initial time savings will be lost. Don’t risk spoiling good tiles with a quick and easy installation that professionals will not back. Check with the tile manufacturer to see if there is a tested one-step method for your tiles that they will back, and recreate that method with the recommended installation products.
– John Dumbrille
Information on these pages is offered as a background and guideline. No warranty is implied. Always check with your manufacturer for an installation method that they will stand behind.