The Studio Journal · Craft

What grout is best for a glass mosaic?


A fine, smooth grout — unsanded, or a modern fine-sanded grout rated safe for glass — in narrow joints, and in a colour you chose as part of the design, not as an afterthought. Coarse sanded grout can scratch glass faces as it is worked into the joints, and wide joints are where grout shrinks and cracks. On our bench and in our shower features, the grout is picked when the glass is picked, tested on a scrap board, and only then allowed anywhere near the finished piece.

Made to orderHandmade for your space
Minimum 30 daysIn the studio, from approval
Christmas cut-offOrder by November 15
From $650Shipping at buyer’s cost

Why glass wants a fine grout

Standard sanded grout carries coarse sand — fine for rough ceramic and stone, miserable for glass. Dragged across a polished glass face under a float, those grains can leave fine scratches that only show when the light rakes across the finished piece, which is of course exactly how mosaic is meant to be seen. Unsanded grout is smooth and safe for glass and for joints up to about 1/8 inch — which is where most hand-cut mosaic lives anyway. Newer fine-aggregate grouts split the difference: smooth enough for glass, strong enough for slightly wider joints, and they are what usually goes into our wet-area work.

Grout colour is half the picture

Dark grout outlines every single tessera — the piece reads as a drawing, graphic and sharp. Light grout lets neighbouring colours melt together and the piece reads as a painting. The same panel can look like two different artworks depending on the joint colour, which is why the choice is made at the design stage, mocked up both ways before a joint is filled. One more glass-specific wrinkle: translucent glass shows the colour behind and between the pieces, so grout colour can shift the apparent colour of the glass itself. There is no substitute for seeing it dried, on the actual glass.

The scrap-board test, and wet areas

Before any commission is grouted, the chosen grout goes on a scrap board of the same glass, dries fully, and gets looked at in daylight and evening light. Grout dries lighter than it looks in the bucket, and a colour that sings at noon can go muddy at dusk. For mosaics fitted inside showers, the grout also has a job to do: a high-performance cement grout or an epoxy grout where the budget allows, sealed where the product calls for it — Colorado Springs water is hard, and fine joints in a daily shower earn their protection. Framed wall pieces live an easier life and simply want the grout kept dry-dusted and out of acid cleaners.

The short version

Fine unsanded (or glass-safe fine-sanded) grout, narrow joints, colour chosen with the design and proven on a scrap board first. Every Lion & Crown piece is made to order by hand in Colorado Springs — small framed pieces from $650, medium panels from $1,200, murals and shower features $180–$250 per square foot — with a minimum of 30 days in the studio and the Christmas order book closing November 15. Questions about a commission? Call or text 719-521-8312.

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