10 tips for working with the mosaic hammer

Mosaikhammer Tipps und TricksSome time ago I was asked to post a few tips for working with the mosaic hammer. Although I have only been attending the school for a few months and wouldn’t claim to be an expert yet, I would like to pass on to you the essentials regarding the use of this wonderful tool. The first points on posture and breathing may seem a little odd. But I realize very often how much they do matter if I don’t pay attention to them.

Some of the suggestions below are things teached here at school, some are based on personal experience. However, I believe that every mosaicista has his tricks. And that’s fine, because we clearly are not robots. So try out things yourself and pay attention to little changes while using different angles, materials and positions.

By the way: Making mosaic has become a kind of mood barometer for me. If I’m in bad temper, nothing works. Maybe this will happen to you, too. So if everything goes on strike: Just take a walk around the block or go and have a coffee break.

10 tips for working with the mosaic hammer

1. Upright posture

Really underestimated: A straight posture. As a potato sack, it is really hard to make a decent cut and your back will hurt in the long run. So rather make a long back, keep the upper arm to the upper torso and work only with the forearm.

2. Wear protective glasses

If you prefer to keep your eyes safe from glass or stone splinters, remember to always wear safety glasses! You don’t like the plastic models from the construction market? Ask your optician to put normal glass in a frame you like and fits you well.

3. Breathe calmly

Who is tense tends to hold one’s breath. Then nothing works well. So just try to breathe calmly and let the hammer fall when you exhale. Can have great effects.

4. Align properly

Might seem trivial, but is really important: If you are too far away from the wooden stump, the hammer can not hit the hardie at the right angle. Furthermore, the cutting surface of the hammer needs to have the same orientation as the surface of the hardie. They just have to fit together, a bit like your upper and lower jaw when your mouth is closed.

5. Use weight of the hammer

Even if some stones require a harder hitting and thus mean more effort for you: Do not use the hammer with too much force. On the contrary: Always try to use only the weight of the hammer for cutting first. So let the hammer fall rather than strike. Otherwise you risk that the widia of the hammer is ruined.

6. Think before you cut

Produce little waste
In the beginning, you tend to start cutting before asking yourself how to organize your mosaic and reflect on the material, producing more waste than necessary. So don’t forget to check these points before starting: How big is my mosaic? How do I divide it into approximately equal parts? Of what size is my raw material? And how can I benefit from its size to create little waste? (If you work with smalts measuring 1 cm x 2 cm, you could work with pieces measuring 1 cm x 1 cm on average, 0.5 cm x 1 cm , etc.)

Create a prototype
Sometimes you lose track on how big or high you wanted the pieces to be and tend to cut smaller and smaller. To avoid that, it is helpful to prepare some “prototypes” you can compare to now and then.

Cut many useful sides
The more proper your pieces are, the more effective you will be in the implementation of the mosaic. Try, therefore, to cut pieces with many clean sides so that you can use each piece in different orientations. This is of course less valid for modern techniques or spontaneous work, but more for traditional mosaics and those in which repeated forms are used.

7. Create proper geometric shapes

Mosaik_dreiecke_schlagenTo cut triangles, first form a cuboid. Then cut two triangles by dividing it diagonally into two equal parts (see right figure). I know you will say: How am I supposed to cut two triangles out of a cuboid without having the corners look crippled ? It works! It is important that the surface of the cuboid is as flat as possible, though, and that you strike as horizontally as possible with the surface of the hammer. If you need an isosceles triangle, just cut off another corner.


To cut pentagons, (see figure at right) of a cuboid cut off three corners in the angles you need. Like this, you should receive at least two clean sides. Do not despair: To cut proper pentagons is really tricky.

Cubes or pyramids?
Depending on which mosaic technique you use, you will need pieces whose top and bottom are shaped in the same way or those that taper towards the (adhesive) bottom side like pyramids.

Mosaik_quader_schlagenIn the indirect technique, for example, pyramid-formed pieces leave sufficient space for the cement which will hold them together later.

To cut cuboid-formed pieces or pieces with the same top and bottom, pay attention to a 90 degree angle when striking (see upper figure at right).

To cut pyramid-formed pieces, there are two options:


1.) Put a piece with a plain surface on the hardie and cut in an angle smaller than 90 degrees so that you get the pyramid shape immediately. This technique requires a little practice, but is then very efficient (see lower figure at right).

2.) Lay a cuboid-formed piece on the surface of the wooden stamp. Hold the hammer directly under its head. Tilt the piece so that it stands on an edge and cut off one diagonal part after the other. This will take you longer compared to 1.) and may be a bit tricky at the beginning. It is a bit difficult to show this process in a figure so I will try to add a video soon to explain better.

Basically, while with 1.) you get a pyramid-shaped form directly, in 2.) you cut away parts to get the diagonal sides afterwards.

8. Be patient

To cut precise shapes, it takes practice. Do not expect to cut perfect triangles after two hours. But you will learn fast. Rely on your common sense and take time to get to know the texture of the material better. You will soon get used to certain techniques and good cuts won’t be coincidences any more.

9. Store hammer safely

Many – including myself – have been annoyed having the hammer landed on the floor because of careless depositing. This can ruin your hammer and the cutting surface. Sharpening could cost you a lot because few have the equipment. So to keep on working with your martellina for many years (some use 50 year olds) always make sure she is stored safely.

10. Stretch yourself

After a few months of intensive work with the hammer, I can only recommend: Stretch as often as you find the time! Your wrists, back and Co. will thank you.


You have more tips and tricks or questions regarding the use of the mosaic hammer? I look forward to your feedback!

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  1. Great post – many thanks! Really clearly explained and I’ll enjoy using your explanations for students on courses at Edinburgh Mosaic Studio and for the talk and demonstration – Ravenna Mosaico: a contemporary craft rooted in history – I am delivering at the Italian Institute in February with Dr Claudia Bolgia, Lecturer in History of Art at Edinburgh University.
    Looking forward to the video when it comes…

    1. says: miriam

      Thank you, Joanna! I’m glad you will use the suggestions in your lessons and talks. Please let me know if the tips are helpful for your attendants!

  2. says: Justin

    Dear Miriam,

    Thanks for the post: I think it is very helpful. Numbers 6 and 7 were just what I was asking about. When I look at a tessera, it’s sometimes hard to know just where to start, in terms of getting the desired shape. I think the diagrams are helpful. Thanks again.


    1. says: miriam

      Thanks for your feedback, dear Justin! It’s great to hear that the post is helpful. Please let me know if you have any more questions regarding the geometric forms.
      Enjoy, Miriam

  3. says: Justin

    Dear Miriam,

    I just thought of two questions about shaping the tesserae:

    1. I have seen in some of your pictures that you begin with a large piece of marble – it looks to be a 3cm cuboid shape or even an irregular chunk. How you do begin to break down the big chucks into smaller tesserae? Is there an organized method?

    2. In terms of the martellina, are you using steel (acciaio) or carbide (widia) to cut the stone? In my experience, I sometimes have problems cutting stone using the steel martellina and I am tempted to use the widia instead for harder stone: I wonder if there is any danger in doing that?

    Many thanks,

    1. says: miriam

      Dear Justin,

      regarding 1.) normally, if you have a bigger chuck you will first cut it into forms you can handle better (half of the half of the half and so on) and then ask yourself how to divide it in the best way to get the hight of the tessera (or better: the height of a row of tesserae). Of course, this all depends on the tesserae you would like to produce.
      Once we have the height of the tessera(e) we cut those parts (width × depth) that will build the surface of the mosaic later. Like this, making a roman mosaic, you can produce a series of tesserae with an equal height and a clean surface. Always trying to produce as less unuseful parts as possible.

      regarding 2.) We use a hammer with two carbide (widia) sides and cut glass and marble with it. As long as the material is not too hard, this should not ruin the widia. But if you see that it is a tough material better use steel. There are also hammers with one part widia and one part made of steel. I have such a hammer, but to be honest I mostly use the widia side because its cuts are much more precise.
      What you should NEVER cut with a carbide hammer is pebbles and material of equal hardness. For this, always use steel!

      I have put both subjects on my post ideas list. Thanks for asking!

      Cheers, Miriam

  4. says: Dee

    Thank you for your great tips. I have just purchased a hammer and hardie about 2 months ago, and it has the dual blade (carbide on one side and steel on the other). I know this tool has been used for many years in Europe. I have recently been reading about potential hazards from working with natural stone in enclosed spaces. The lung damage by silica dust from natural (particularly marble dust which can easily become airborne) is of some concern. Do you use any masks or take any personal precautions to protect your lungs from irreversible damage? I’ve been doing my cutting with hammer and hardie outside on my screened porch to minimize inhaling concentrated fine dust and other possible gases or hazards that can be more concentrated when working indoors.

    1. says: miriam

      Hey Dee, very good question!

      I am aware of the fact that the dust of material and also cements and glues can harm lungs, skin and eyes. I am always the first one in class to open windows and try to not produce too much dust when I prepare the mortar.
      We don’t protect ourselves by using masks or anything, though. It is just not very comfortable to use them all the time. But I guess you do well to do this or to work outside if you can.

      I talked about this matter with a mosaicist lately. And she told me there are many people who have their nose running all the time because they have evolved a kind of allergy or suffer of other problems. My eyes are burning since three months, because it seems I am allergic to something, too. So I went to the oculist and will now probably find out soon. Maybe it is the cats that I have been living with since July.

      I don’t really know what to tell you. Better exaggerate protecting yourself. I am thinking about how to do this more, too. We only have two eyes and a lung and I don’t want to be forced to give up doing mosaics because of any health problems.

      Thanks a lot for your comment. It has made me reflect some more about this subject!

      Best wishes

      1. says: miriam

        Levitra, at the end with all that theory what you need to do in fact is practice. You are not out of league! Just deserves some attention, and many things will also come naturally!

  5. says: Naffati

    Hello Teacher,

    Many thanks for this tuto, If I were a disabled person in a wheel chair, which posture must I adopt ? many thanks

    1. says: miriam

      Hello Naffati, I guess you should find out what is the best posture trying to sit on the right or left of the chunk and turning your torso towards it. Sitting in front of the chunk could make you be too distant and cause you back aches. Let me know how it worked please so I can share with people. Best regards and enjoy your work, Miriam

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