The choice of sculpting stones - soft stone or hard stone?

In principle, anyone can work with any stone. You don't necessarily have to start with soft stone as a stone sculpting novice to take your first steps, although you usually need less technical skill with soft stone. What matters most is the challenge you are looking for, how much time you want to spend and sometimes whether you have support or guidance in the work.

The hardness of the stone

As early as 200 years ago, the mineralogist Friedrich Mohs established the scale for classifying the hardness of minerals that is still valid today. Rocks are also classified according to this scale, although they do not always have a uniform hardness because they consist of different minerals.

Mohs established a division into 10 degrees of hardness: the mineral talc has hardness 1 and makes up the main component of soapstone , for example. At the other end of the scale is diamond, with a hardness of 10.

The distances between the 10 levels are not always the same: the first five degrees of hardness are much closer together than the further gradations.

Stone masons speak of hard stone (e.g. granite) from hardness 5, marble with a hardness of 3 to 4 is still considered soft stone for them. Anyone who has ever carved marble may, however, be surprised at how much work it takes to carve this classic of sculpture alone.

How hard or firm a stone actually is depends on various factors: Sandstone, for example, is composed mainly of quartz, but appears much softer than hardness 7 because the bond between the quartz particles is often soft. Also for limestone , the looser the bond, the softer it is experienced.

Here in the bildhau shop you will always find information on which types of stone and for which degrees of hardness, for example, certain tools are suitable. At bildhau we distinguish as follows:

Marble soft: up to about hardness 3 of the Mohs scale
Marble hard: from hardness 4
Limestone soft: up to about hardness 2.5
Limestone hard: Hardness 3 - 4
Serpentine soft: up to about hardness 2.5
Serpentine hard: from about hardness 3 - 3.5 (e.g. Springstone)

Sculptor's questions before stone selection

Before deciding on a stone, it may be useful to ask yourself a few questions in order to make a good choice. We would like to give you a few of them to prepare yourself – if you do not have much experience with stone yet – for buying stone:

• Do I want to work the stone by hand or by machine ?
• Do I want a soft stone that I can work with a rasp and sandpaper, or a stone that I strike with a chisel and a mason's hammer or a mallet?
• Do I want to work spontaneously and quickly or do I take my time to find the shape even with a hard stone with which I may only make slow progress?.
• Do I attend a weekend sculpture course and want to have a finished sculpture at the end or do I want to work continuously and for a longer period on a stone?
• Do I have a specific idea or model that I would like to implement and that makes special demands on the material?
• Which tool do I already have and which rock can I work with it?
• Am I willing to invest in other tools regardless of the choice of stone?
• How many kilos of stone can I move?
• What kind of finish or colour do I want in the end? Do I want to be able to polish the stone ?
• Do I want to place the stone indoors or outdoors?

But it also works quite differently: you see a stone, „fall in love“ with it and just go – and forget all other questions!

Which tool for which stone?

If you choose hard stone, for example, you will need different tools than for soft stone such as soapstone or alabaster – you should bear this in mind when choosing a suitable sculpting stone. bildhau will be happy to advise you on this! Newcomers can also gain initial experience in sculpture courses offered in many places.

Sculpture stones from all over the world made to measure

We always have a selection of sculpture stones in stock for you, but we don't always have all the stones in stock and not all sizes are available. There are many reasons for this: Some of the stones come from very far away and are not always available there either. Often, only blocks of 12 tonnes and more are traded, which means that cuts have to be ordered, which first has to be organised on site. In addition, our buyer checks the quality of the stones in advance. In order to keep the transport costs within acceptable limits, stones are collected from different quarries and only then sent on their way to us.

In our large warehouse in The Hague, we can also make our own cuts. If you are looking for a specific stone or format, simply contact us before your visit to Cologne. We will try to meet your wishes as best as possible. Of course, you can also purchase all standard pieces in the online shop or order custom sizes from us best by phone.

If you would like to visit our warehouse in The Hague to choose your sculpture stones, even larger ones, directly on site, please contact us as soon as possible.

The following types of stone are usually in stock at bildhau :

Soapstone – soft stone for spontaneous and quick work

Soapstone is found in many places around the world in a wide variety of colours and textures and is easy to sculpt even with simple tools such as rasps and files.

Alabaster – translucent natural stone in various colours

Alabaster is a semi-crystal of gypsum and usually somewhat harder than soapstone, but still belongs to the softer types of stone. Characteristic for the natural stone is its transparency and its crack structure. Alabaster is available in various colours.

Serpentine – fairly traded from Zimbabwe

Our Serpentine comes from Zimbabwe, it is related to soapstone and is stored in metre-thick chunks close to the earth's surface. The serpentine sourced from bildhau is mined and traded fairly in cooperation with the local population.

Marble – the sculpture classic

In addition to the very classic white Statuario, there are many variations of marble from different countries around the world, e.g. blue marble from Brazil, pink Aurora marble from Portugal, grey Bardiglio and black and yellow veined white Paonazzo from Italy.

Limestone – from brittle to hard

Limestone is formed by the sedimentation of shells and skeletons of small marine animals. The hardness of limestone depends on the bonding of the limestone particles, so there are very open limestones that are easy to carve, but also very dense limestones of a hardness similar to marble.

Travertine and onyx

Travertine belongs to the group of limestones. However, it forms in freshwater lakes as a result of lime deposits on the bottom. During this process, gas formation creates small and large holes in the rock. This gives travertine its attractive appearance, but it is not always so easy to work.

Onyx is a trade name for sintered limestone, which is very close to travertine in terms of formation history. Onyx also forms as limestone precipitate, but in hot water springs with mineral impurities that form surprising, beautiful colours. Due to its special lime structure, onyx is harder than marble and limestone and rather difficult to work with.

Sandstone

Sandstone, like limestone, is a sedimentary rock, but consists of at least 50 % sand grains and usually has a high quartz content. It is not uncommon for the term sandstone to be applied to other types of rock, but these are often limestones with sand stains. Sandstone is found all over the world, including Germany. Sandstone is a classic sculpture stone that comes in different degrees of hardness. The decisive factor for the hardness is the bond, because sand alone is always equally hard. bildhau does not currently have any pure sandstones in its range because of the high dust exposure.