12/07/2023
What is mastic and why can't I use it everywhere? It seems super convenient doesn't it? A premixed bucket of tile stick 'em, just open, spread the white goo and voila! No heavy bags, no dust, no electric mixer needed! Seems almost too good to be true....because it is. Mastic has been around for a while and interestingly, it used to be made from the sap of the mastic tree! (Pistacia lentiscus for all the plant nerds). Now, mastic is mostly acrylic co-polymers and calcium carbonate. While mastic is not a one-stop shop for all your tile sticking needs, it is suitable for some things. It can be used on a backsplash area like a kitchen or bar or potentially a floor area. Some place where it will be dry, kept a consistent room temp (not too hot or too cold) and have minimal traffic. Keep in mind though, the tile you're using must also be suitable for mastic. Glass tiles are never suitable for any sort of mastic, neither is a full body metal tile. While you might want to lay that large format porcelain floor tile with it, you can be sure the chances of that mastic ever curing to its full potential to support that tile are slim because the amount of adhesive you'll need is substantial, and porcelain has almost no absorption rate when it comes to moisture. Mastic must be able to dry to achieve a full bond, and setting tiles that are almost completely vitreous (meaning they don't absorb moisture) is a sure-fire way to wind up with an install that never sets up. Mastic should never be used in conjunction with a waterproof membrane like Kerdi, Ditra, Redguard or similar. There are factors at play beyond just drying time that will negatively affect this install. Mastic should not be used in wet areas like showers as it will grow mold and mildew and constant exposure to water can cause it to liquify. A pool of liquidified mastic in a shower floor with a tile topping is just gross. I've seen it. The best way to know if the tile you're using and the area you want to install it in is ok to use with mastic is to consult both the manufacturer of the mastic, and tile. Read the packaging labels, go to the company websites, or call a customer service rep. You can also find information in TCNA and NTCA handbooks. If you're spending alot money on an install you want to know it's going to last so it pays to do your homework!