Why these flexible adhesives earn a place in your studio.
When you’ve been laying tile long enough, you learn the truth: not every adhesive is built for mosaic work. Some dry too brittle, some yellow, some lose their grip the minute you put your trust in them. And some—like silicone and Lexel—quietly get the job done and rarely complain.
Lexel is my rubber-based adhesive of choice, as it seems to be far less "fumey". I have actually gotten what I call a "silicone hangover" from using other brands. Read the manufacturer's directions for use and precautions.
These “modern” adhesives aren’t exactly new, but mosaic artists have been leaning on them for years because they solve problems the traditional glues can’t. If your work involves glass-on-glass, outdoor installations, or surfaces that expand and contract, this is where silicone and Lexel shine.
Let’s break it down.
Why Mosaic Artists Reach for Silicone
Silicone has been the go-to adhesive for glass-on-glass projects for decades. It’s flexible, durable, and crystal clear when you buy the right kind.
Where Silicone Makes Sense
- Glass-on-glass mosaics: Stays transparent, holds glass securely, and won’t yellow if you use a 100% silicone that dries clear, unlike WeldBold, which can take days, even weeks, to dry and turn clear. These start clear and cure clear.
- Outdoor or weather-exposed pieces: Silicone stays elastic. Temperature swings, rain, humidity—none of it fazes it.
- Flexible substrate: When your substrate is flexible, you need an adhesive that will flex with it.
Tips to Use Silicone Well
- Choose 100% clear silicone, not “translucent,” not “window and door with additives," and definitely not anything mildewcide-loaded for bathrooms.
- Work in small sections—once it skins over, you lose tack.
- Use toothpicks or skewers to manage squeeze-out.
- Don’t grout over silicone. Keep it strictly under-glass or under-tile.
- Clean-up requires acetone (fingernail polish remover).
Lexel: Silicone’s Tougher Cousin
Lexel doesn’t get as much attention, but it should. It’s a solvent-based elastomeric adhesive/sealant with grip that borders on ridiculous.
Think of it as silicone with a backbone.
Where Lexel Outperforms
• Outdoor wall art or garden mosaics: It sticks to almost anything—stone, metal, wood, glass—and stays stuck.
• High-movement surfaces: Think of substrates that expand and contract or flex. Lexel won’t crack.
• Mixed-media mosaics: When you’ve got glass, stone, ceramic, and a mystery piece from the thrift store all in the same project, Lexel levels the playing field.
We have successfully used Lexel on several metal and glass bases that "live" outside in Wisconsin. Lexel is a copolymer rubber. Great for those weatherproof applications where a clear adhesive is required or if you are working on a metal or other composite substrate, such as fiberglass.
Lexel differs from silicone in strength and will not yellow over time.
Using Lexel Like You Know What You're Doing
- Choose clear Lexel for visible areas—it dries much clearer than silicone.
- Ventilation matters. It’s solvent-based and has a smell that means business.
- Cure time is longer than silicone, so build that into your plan.
- It’s self-leveling, so don’t over-apply unless you enjoy cleanup.
Common Mistakes (and How to Avoid Them)
- Using too much adhesive - Both products bond best with a thin layer. You don’t need frosting—just coverage.
- Trapping air bubbles - Press and slide your tesserae slightly to release air before you set them in place.
- Buying the wrong formulation - If the label has the words “kitchen,” “bath,” “mildew resistant,” or “paintable,” walk away.
- Rushing the cure - Silicone and Lexel need time to fully set. Give them 24–72 hours before grouting or moving the piece.
Why These Adhesives Still Matter Today
The mosaic world is full of new products, boutique glues, and fancy-sounding bonding agents. But when you strip away the marketing, silicone and Lexel have stood the test of time for one simple reason: they work.
They don’t get brittle. They don’t peel off. They don’t mind a little weather. And they handle the realities of mixed materials better than most products designed for mosaic work in the first place, except Thinset.
I personally choose these types of adhesives only when I need it to be transparent and/or more flexible than cement-based thinset. As the daughter of a tile setter, thinset is always my first choice, but everyone has to break tradition if the substrate calls for it.
