I like to use press moulds and hump moulds as opposed to slip casting because there are less variables to ensure consistent results. To help with consistency I built a mini slab roller. The design concept comes from a video posted on Ceramics Art Network – How to make your very own Slab Roller.

Since I currently do not have the ability to fire large pieces, I built this roller to a dimension that would pack away in a cupboard easily. It is essentially a good working prototype which I would feel comfortable scaling up in the future.

The slab roller consists of 10 components with some additional fixings and cables. For the structural components regular plywood has been used. For the bed of the roller two 18mm pieces were glued and screwed together.

Each piece of plywood, as it is not marine grade, was sealed with a white waterproof paint. I realise that white will not stay white for long but it is what I had on hand. Essentially, it is just to provide a wipeable surface.

Steel box section was used for the rails, however any none compressible material could be used. I was hesitant to use plywood for this part as it is important that they stay flat and do not develop ripples or ridges over time or these imperfections will be translated into the slab.

Everything is screwed together, I did not see the point of any fancy joinery. The legs are only supporting the weight of the clay and bed. There is no stress or strain created at these so I just did something that works.

At this stage, the tensioning knobs are free to spin. They are just a plywood circle with a hole drilled through to enable the cable to be thread through.

The tensioning method I decided to use worked quite well. Initially, I was unsure if my cables would stretch so I wanted to have something easy to change. One end of the cable is fixed, simply just using a washer and a plastic stopper and a figure-8 stopper knot. The other end is then fed through the tightening mechanism.

Once each cable is fed around the top and bottom rollers in the figure-8 configuration, I then tightened the tensioning knobs as tight as I could turn them by hand. I then simply screwed the knobs down.

Lastly, I inserted a melamine laminated particle board as the rolling surface. This melamine board is sized to fit very well but loosely. I use this for a couple of reasons. Firstly, it is a cheap disposable surface. Secondly, it is very flat. Thirdly, by having this loose I can vary the thickness of the slab by raising or lowering this melamine board. I do this by placing a number of linoleum sheets between the plywood bed and the melamine board.

Cable Figure-8 arrangement. The copper wire which is present on the lower roller is only required since I had quite a short length and was worried that it would not track evenly and the cable would slip off. This wire just helps prevent the lower roller from moving one way or the other.

Conclusion

I think perhaps next time I make a slab roller I would make it wider. This prototype was sized based upon materials. My lower roller really limited the width. Next time I would consider an extra 50mm-100mm but the size of this roller is really specific for my needs. – I believe this design is capable of being much larger. And if using the right materials would work sufficiently well rather than buying a commercial product.

If I was to make this larger, I would use steel cable. I suspect that my cable stretches a bit as I am using the roller which results in the need to make two passes to ensure the slab is even. Preventing the stretch is key to a single pass flat slab.

If I was to make this again, I would consider thick wall PVC pipe for the rollers or some other non-stick material. This also holds true for the melamine board. I suspect I would still require some form of release for the clay but currently galvanised pipe is an especially poor surface and any form of contact with clay causes sticking which is then imprinted into the slab. This forces me to use cloth on both sides of the clay. This is not a big problem but could be if you require specific measurements of slab thickness and you do not include this in you initial construction considerations.