A Recycled timber wooden mosaic substrate frame

A Beginners Guide to Mosaic Substrates | How to choose what substrate to use for your mosaic project

March 20, 2026

Let's Talk Substrates

Substrates are what your mosaic is glued onto.

The main thing you need to remember when thinking about what substrate you want to use is first thinking of what the substrate is made of and where you want to display your project. If you left your substrate where you want to display your piece, would that material survive in those conditions?

For example, I know if I'm creating a piece I want to display outside, I can't use wood as that will swell in the weather and destroy my art piece. But if I put my piece onto a concrete paver that increases the life span of my mosaic piece to as long as the concrete paver would survive in its place.

Types of Substrates for Mosaics

Have you heard that comedic skit, "Everything's A Drum"? Well Substrate is pretty much the same. Everything's a substrate!

Looking for a good substrate though, now that's a different story. What you want is something solid, doesn't flex or swell in the weather it will be exposed to, is porous so your adhesive has something to stick to, and is going to last the test of time in your chosen conditions.

A Beginners Guide to Outdoors Mosaic Substrates

So think rigid construction materials.

Concrete- Can be shaped into infinite possibilities through the use of molds, pot bases for pavers are an easy at home project. Very versatile. Available readily. Can crack and swell in freezing temperatures.

Check out our Beginner's Guide to Making a Concrete Paver to use as a Mosaic Substrate

Cement Sheeting/Board- Great weather resistant properties, but i find it quite brittle. Great for portable outdoor large projects as with a masonry jigsaw blade as long as your corners aren't too tight its quite manageable.

Natural Stone/Slate- I haven't used slate as a substrate personally

Compressed Fibre Cement- I presume this would behave like the cement sheeting, brittle but very weather resistant.

Terracotta Pots- Terracotta pots need to be sealed as they are constantly absorbing water so can dissolve your adhesive. But otherwise, a solid substrate choice when prepared properly

Plastic? - no just don't, it breaks hearts around the world of beginner mosaic artists when they attempt the plastic substrate that ultimately falls apart.

A Beginners Guide to Indoor Mosaic Substrates

Bringing your piece indoors essentially opens up all the wooden products available at the hardware store, think thicker unmoving wooden materials.

Plywood

When creating Mosaics 6mm plus thickness plywood is my go to I like to get the Marine grade ply as i figure its more moisture resistant for projects like coasters that might experience the occasional spill. Plywood is also affordable, easy to us and ready adheres using my PVA based glue I prefer.

The only major downside to using plywood as a substrate is it doesn't look nice raw so you must cover the entire face of your pattern with tile and grout for it to be aesthetically pleasing.

Check out our guide to preparing plywood for mosaic substrate

Timber

The generic term of timber literally covers everything and for a reason.

As long as the timber has been dried correctly you should be able to confidently use it inside without it warping.

Timber is effected by moisture, by the moisture inside it just as much as the moisture it's exposed to from the outside world. Wet internal timber is called green timber and should not be used as when it dries it will shrink and warp and ruin your drid solid mosaic.

I love using recycled timber as a base for mosaics if I'd like to show a wood grain as the background to enhance the piece. Because I use recycled timber, I make sure it is air dried in a covered area for a long time before it is used at a base for my substrate to make sure it's in its final dried shape.

I'm Sure there's lots of other substrates for indoors but I don't have enough experience on them to confidently comment on them.

In Conclusion

When it comes to choosing your substrate, most people enter the mosaicing scene with a project in mind. They've seen a statue or step and a light bulb has set off the passion. So the substrate is worked around.

If that is the case, you'll more than likely need to prep what you have ready to apply your tesserae. The surface needs to be rough so the glue has something to grip to, it needs to be kept where it's likely to need less maintenance and repair to maintain longevity of life. It might pay to waterproof, there's water proofing membrane, down to a few layers of sealer coat beforehand.

If in doubt over engineer, mosaic is a slow art. So, to lose your very hard earnt work to bad substrate preparation or the wrong substrate use for its intended purpose is incredibly heart breaking.

If you have come in with a design and are working around that. Start with location, will it last? What prep is needed to extend that life as long as possible? Will it absorb water? Will it fade in the sun? Do I have it on hand already? Can I protect it? Will it protect my art piece?

If you get lost start with our beginner kit series and I'll guide you through your mosaic creation journey.