How to make Rustic Abstract Mosaics with Slate, Stone & Glass

Can you believe it?! There’s ways to make beautiful art without the typical pressure of high level skills. You know how much I love nature so this easy project is even more exciting! Won’t you join me as I share how to make Rustic Abstract Mosaics with Slate, Stone & Glass.

You may remember how I have been making my own Tesserae from found things like plates, vases and other glassware. It’s fun to constantly be on the lookout for interesting (and often free) supplies! Another realization I had is that I can use what is found in nature – rocks and stones!

In this technique the tesserae is adhered in a way that does not need a full grouting when done. It’s as simple as; prepare the board, mix the thinset/adhesive, spread, place and wait…

Once I dove down that ‘rabbit hole’ of using natural stone I also discovered the natural beauty of Slate! It is a lovely stone to work with since it can be used in multiple forms. I am able to buy bags of chunks (smaller pieces) here in Canada at a garden centre. Slate as a building material also has a historical factor; it was & still used as roof shingles. It is strong and flat, and will often break apart from it’s multiple layers. Did I mention it is quite hard?! Check around, you may find roof tile remnants. I have also found some at an antique market. You may be able to find a range of slates.

I was also able to find some unique red slate at an aquarium supply store where it is sold for making habitats for reptiles. Going for hikes will also yield some new additions; yes I was the kind of child who would bring home pretty rocks…

How to work with Slate:

Here, I am geared up with eye protection, apron and gloves. I love the random slate pieces but I also want to add another design element to my choices for mosaic; slate rods. Slate can be cut with a wet tile saw quite easily.

I obtained a few slate roof tiles that are less than 1/4″ think. I like the repetitive nature of lines in design so I am cutting long thin lines of slate called rods.

My inexpensive wet saw was bought to cut ceramic tiles. It has a reservoir that holds water, keeping the blade wet for easier cutting. It is a loud & messy job, so you want to cut quite a bit when you do it. The guide can be adjusted to make sure that the strips are all same width. Slide the slate along as you would on a table saw, fingers well away from the blade! Tip, keep the protector hood down over the blade, if you raise it the water will spray into your face (don’t ask how I found out).

The water that collects in the bottom also becomes a sludge of slate dust. Do not pour any of it into the drain! I plan on trying my hand at making some paint so I will dry this into a pigment powder. (more to come) It is a whole process that is quite messy…

The rods hold quite well at 1 cm wide. You can still make great designs without sawing the slate if you so choose to avoid the ‘monster’ saw. There are so many options, the more unique choice of shapes and materials the better!

After cutting the slate will need rinsing (outside or in a bucket). You can create smaller shards as well with a hammer. (protect eyes and surroundings) I often like to do the ‘rock breaking’ outside, and use a large rock that stops pieces flying everywhere.

Rustic means less Perfection:

Since I am a nature lover this mosaic method really appeals to me since it less like traditional mosaic work. ‘It must be because it relates to those beautiful views of mountains & rocky trails. Feel free to add other elements like beach stones, shells, or other rocks. The abstract designs pretty well allow anything. The elements of design are: line, shape, space, texture & pattern – all very abundant in nature!

The imperfections and uncontrolled details accent and contrast perfectly; such beautiful wall sculptures. That thrifted nubbly glass vase (make your own tesserae) looks quite organic once roughly cut. The juxtaposition of some glass in slate mosaics works quite well.

How to create a design:

I’ve heard it so often; ‘I can’t come up with a design’. When we are forcing ourselves to just visualize a design we usually draw a blank in our mind. Once we are relaxed, less pressure, we can dream up more. Take some paper – doodle & sketch. Another way is to find a picture and isolate a small section that appeals to you, replicate those shapes into a design, it can be that easy. Abstract art speaks in a different way to our soul. Trust your gut instinct…

A few flowing lines can lay out the design. I often like to just let the material ‘speak to me’ and work as I just see fit; piece-by-piece. Since most of the supplies are inexpensive it is refreshing to be free of certain expectations.

What material to use as a mosaic substrate:

The best base material to use is one that is engineered for tiling. Depending on your country there are backer boards available at your local hardware store. They come under names like Wedi-board, Schluter, Thermasheet and more. The key to a having a good substrate is that the material does not expand, contract, or bend. The tesserae will bond much better if the material is stable no movement. If there are any chances of cracking then the pieces may fall apart.

In my experimentation MDF is known as an acceptable substrate to use indoors. It should be sealed first to eliminate it from taking the moisture from the thinset (or tile adhesive) used to set the tesserae (mosaic pieces into). Over all my years of making stuff I was hesitant with the use of MDF as it is a fibre-based material but it worked for the small pieces.

Things to consider when making mosaics:

I much rather use a very solid material that does not have the ability to absorb water; like a flat piece of rock. Concrete (pour your own) or slabs act similarly to a large stone. They work great but the added weight can be an issue if wanting to hang on a wall. Marine plywood is similar to MDF (medium density fibre-board) but also needs sealing.

The professionally engineered boards have a centre material that does not absorb moisture and is also light weight. To give strength a dense outer layer and also fibreglass mesh reduce expanding/contracting and make it rigid so less likely to bend. Consider the size of the piece when deciding how bendable the substrate may be.

As I understand, you could also make your own substrates by adding a layer of thinset and fibreglass mesh to some styrofoam (polystyrene). That method could even allow the building of 3-dimensional substrates. The Schluter boards also allow the attachment of hanging hardware through the board quite easily before adding the tesserae. You do not want a heavy piece of art falling off the wall and potentially hurting someone! I plan on some DIY making of substrates in the near future.

What to use to attach the Tesserae:

This style of mosaic art is usually not grouted. I use a tile adhesive or Thinset. The different brands often come in fortified or unfortified versions. The addition of the polymers helps fortify (strengthen) the final product and prefer that.

Thinset or tile adhesive is used to set the tesserae design into. You should aim to have about 2/3 of the depth of the tesserae inbedded into the thinset.

These abstract mosaic designs are often less particular so the pieces can have some of the background showing through. For that reason you should decide what colour best suits your design – I often like the dark charcoal colour. I am using Versabond polymer fortified Thinset and adding some iron oxide to darken the colour. I have also used acrylic paint to darken (do not exceed 10% by volume).

Mix the Thinset according to manufacturers instructions (wear a dust mask during any work with the powder forms, preferably outdoors). A consistency of about a creamy peanut butter works well. It is often suggested to let the thinset ‘slake’ for about 5 minutes. That probably allows the polymers that are in the mix to congele with the water.

I mix only enough adhesive for the time frame I have and then place it into a small ziplock bag, tape it shut and snip the corner to apply like ‘cake icing’.

Applying the design:

The size of project may dictate how much of the adhesive you apply at once. Since I had the design sketched on I only applied the adhesive/thinset to area I was working on. A pallet knife helps spread the thinset flat. It also helps to have tweezers to keep fingers clean and work with very small pieces of glass and stone.

I find this art form to be really relaxing since most of the pieces are already prepared. I may only need a bit of snipping with the tile nippers (or snapping with the running pliers). It is a free-form way of zig-saw puzzling! The wide range of materials adds a lot of aesthetic interest.

As a visual aid I do keep the colours and materials sorted – much better for the brain.

What types of Tesserae to use:

Tesserae refers to the small pieces that make the mosaic art. Let me (try to) list all the things you can use: Slate (rods and chips), broken stones, broken crockery and ceramics, cut pieces of stained glass scraps, smalti, vitreous glass tiles, cut up-cycled glass, beach stones, wire, beads (not plastic), crystals, gems, cast concrete, stone tiles and more (I’m sure I’ll think of more…) The options of materials are endless, look for a variety of colors and unique shapes.

Smalti is lovely since it has a rustic nature that reminds me of historical mosaics. It can also be cut with the nippers or if you want to be a true mosaic officionado; use a hardie and mosaic hammer to break the pieces as you like. The above blue swirl is a combination of smalti and some cut vitreous glass tiles.

The ‘lines’ of grey are the slate rods that were cut about 1cm from the slate roof tiles. In art there is a term; ‘line quality’, meaning how much character a line(s) can bring to a piece. The slate rods add so much character & texture. This is where stone mosaics differ from the the typical bright coloured ones. There are so many types of stone, marble or other rock that can be included by the mosaic artist in this technique.

How to display your rustic Mosaic:

The combination of texture is very on-trend lately in the abstract art world. We thirst for some tactile, physical objects since so much of our day is in a digital sense. Mosaics can be for decoration as well as function if tiling.

Small deep frames allowed for easy attachment of these smaller panels. I attached the small panels with 2-part epoxy onto the backing board. The white shards I used in the design are roughly cut broken plate pieces.

I added a little bling from the huge vase that I broke and cut into tiles. It has become common practice to see me wielding a hammer and heading into the basement… So satisfying!

Don’t be fooled, it is often the presentation that will make a piece stand out. I used to joke when I was in art college that any awful art can look amazing when framed and presented seriously…

These clean crisp shadowbox frames provide a modern display for the grey slate natural stone surface texture. It adds so much ‘importance’ to a simple piece of art. Enjoy; see what you can find and use! I hope I have inspired you to create your own unique pieces of abstract slate art!

Who knew a piece of slate could make such masterpieces!