Thinset Mortar is concrete with polymers added for enhanced strength and adhesive properties and is the recommended material for all outdoor and wet mosaics (pools, fountains, etc.). Unhardened thinset looks more or less like wet concrete, but it is sticky almost like honey or tar, and handling it for the first time can be a little intimidating. However, with some basic planning, you can eliminate a lot of the mess and all the stress.
One approach is to pre-mount your tiles on paper or mesh so that the final installation only involves trowels to spread thinset on a surface instead of placing individual tiles by hand into thinset.
But what if you want to mount individual tiles by hand and use thinset similar to how you use a convenient bottle of glue to make indoor mosaics?
Well, it doesn’t make sense to try to apply a small amount of thinset to the back of an individual tile similar to how people will sometimes apply glue to the back of a tile from a squeeze bottle. That approach continually contaminates the fingertips with thinset. Instead, it is more efficient and cleaner to spread a little bit of thinset over a small area of your surface and press tiles into that. Small trowels, old butter knives, palette knives and even popsicle sticks are useful for this.
These same spreading tools are also useful for pushing the tiles around and making slight adjustments in position, but invariably artists will use their fingertips for this purpose once they “get in the groove” and lose themselves in the creative flow. And then there are all the plops and spills and silly accidents like picking up the spreading tool from the wrong end.
The question becomes how do you keep your tools and hands clean without consuming a large amount of rags. Remember, this isn’t water or even glue that you are wiping off. It is concrete with sand it it. While you might be able to use the same rag all day when working with Weldbond or some other water-based glue, you can make a rag more of less unusable with just a few wipes of thinset.
Without a system, you will use up an astronomical amount of rags and still have dirty hands. It just isn’t possible to reach for rags randomly without eventually grabbing one that is already contaminated and smearing wet concrete across everything. And it is always the rag that looks perfectly clean that bites you! When the material in question is thinset, it only takes a pea-sized amount to make a big mess.
My Three Rag System
Mosaic and other crafts are more enjoyable and productive when you organize your workstation so that tools and materials are close to hand. This is doubly true when you are working with a messy material like thinset. You’ve got to set things up in a way that takes into account that you will frequently need to clean your hands and tools.
Here is how I use three rags in different ways to maximize the useful life of each rag:
- Dirty Rag: a contaminated rag lying on the work surface near the art.
- Wet rag: a rag is floating in a 2-gallon bucket half filled with water.
- Dry Rag: a clean dry rag lying in the artist’s lap.
The dirty rag is placed directly on the mosaic or work table, right beside the place on the mosaic where I am currently mounting tiles. This is the rag used for wiping clumps of thinset from fingertips and tools. (Note that you should try to shake off large clumps of thinset into a garbage pail first.)
The wet rag floats in a bucket half-filled with water. Hands and tools are dipped into the bucket to rinse them off. The wet rag stays in the bucket and is only there to provide something to rub against to help remove any last traces of concrete.
The dry rag in the artist’s lap should only be used for drying hands and tools that are free of concrete and merely wet. Once the dry rag is contaminated just a little bit, it more or less has to be demoted to being used as the dirty rag. With that in mind, you have to be disciplined and resist the urge to grab it to wipe away spills and smears on the mosaic. For this reason, you should have a fourth rag for emergencies and use it only for that purpose.
In addition to the three rags used for cleaning and drying hands and tools, a fourth rag is needed for cleaning drops and smears on the mosaic itself. Of course, you should always try to get most of the material up using your trowel or spreading tool and use the emergency rag only for the residue so that it lasts longer. Once the emergency rag becomes too contaminated, it is demoted to being the new dirty rag.
Additional Materials and Tips
It takes a little practice to be able to lose yourself in your work and still be disciplined and conscious enough to not grab the first rag you come to when you make a mistake. That is why you should have a box of extra rags standing by. You should also have a bucket by your feet for quick disposal of contaminated rags.
Rinse Your Dirty Rags Outside
Remember to take a break and run outside to the garden hose and rinse the thinset from these rags before it hardens. These rags might be permanently stained, but they can be cleaned sufficiently to be as useful as new rags in the studio. If you are only an occasional artist, this need to reuse rags might not be such a big deal, but if you work with thinset on a regular basis, the amount of rags consumed can be significant. There will always be some that are past saving, so we try to salvage what we can.
Use a Garbage Pail
Another tip is to have an old garbage pail at your workstation so that you can throw old clumps of thinset into it instead your dirty rag bucket. I put scraps of cardboard and trash in my garbage pail to that I have something to wipe my spreading tool on. I try to use the garbage pail as much as possible to take pressure off my dirty rag.
Recycled Plastic Grocery Bags
Most artists tend to work until they can’t work any more, and that makes clean up all the more burdensome, especially when clean up involves wet concrete and requires some actual labor. This is when people are tempted to just grab all their contaminated rags and use them to wipe the left over thinset out of the mixing bucket and just throw them all away and be done. Again, this might be acceptable for an occasional artist, but it really isn’t very “green” or sustainable in a studio that frequently works with thinset.
The good news is that there is a readily available waste material that can be used as a disposable wipe for rubbing thinset off buckets and tools. Plastic grocery bags work very well for this and can be gathered for free in as large a quantity as needed.
Medical Examination Gloves
Thinset and grout contain portland cement and are mildly caustic. We wear disposable latex medical examination gloves when we work with thinset to keep it from drying out our skin.