Criteria for the selection of stove stones
The stones for the stove must withstand the bath microclimate with dignity and take root in conditions of high humidity. The selection of durable fuel should be based on the following factors:
- heat resistance and strength;
- size and weight;
- environmental Safety.
Heat resistance and strength
Bath stones are required to perform one task - to quickly heat up and keep warm. Heat capacity and heat resistance determine the service life, steam volume in the steam room and the rate of material consumption. Suitable stones have three characteristics:
- structure porosity
- high specific gravity
- homogeneity (without impurities).
The most heat-resistant rocks are dunite and jade. The service life of this fuel reaches 10 years. For other breeds, the average use period is 3-4 years. At the end of this time, the stones crumble and get dusty.
Checking fuel for durability is as follows: stones are hit with a metal hammer or bang against each other. A voiced sound speaks of the high quality of the material, a dull sound of mediocre quality.
Size and weight
The size of the stones is selected based on the type of sauna stove:
- a sauna with an open stove, when the air warms up to one hundred degrees, it is heated with large and medium-sized stones;
- the electric heater will need small pebbles (4-6 cm). We need carefully polished stones, the edges of which do not deform the heating parts;
- for wood stoves, stones of medium and large fraction are used (6-18 cm). Smaller specimens are hammered into the holes of the oven grate;
- in a classic bath with a closed oven, stones are selected based on the dimensions of the door for supplying water.
Environmental Safety
When looking for stones for a sauna stove, it is important to take into account that some natural materials are harmful to both the environment and the health of the owner of the sauna. For example, granite often contains radionuclides in its composition. The regular use of such stones for heating generates a small dose of radiation, which negatively affects the body.
Not suitable for stoves and stones that form an embankment near the railway. These materials are processed with creosote. Creosote is a persistent chemical that does not weather or wash off. In elevated temperatures, railway stones emit poisonous steam. The same rule applies to boulders from construction sites and dumps.
Types of stove stones
There are different ways of classifying the stones for kindling stoves. By origin, the breeds form three groups:
- sedimentary (shale, sandstone, limestone);
- metamorphic (marble, slate, quartzite);
- magmatic (basalt, granite, volcanite).
The first two groups are characterized by increased softness. In the structure of sedimentary and metaphorical stones, faults are observed and sometimes contain moisture. Under the influence of heat, such rocks crumble and smoke. Igneous rocks have the highest thermal stability. The exceptions are obsidian and pumice:
- obsidian is too smooth for a bath. Water flows down the surface quickly and does not have time to evaporate;
- due to its low weight and deep pores, pumice is cooled instantly and is not able to maintain the temperature in the steam room for a long time.
For stoves, not only natural but also artificial stones are used. Among artificial materials, the following are popular:
- cast iron cores: thermal conductivity of cores is 30 times higher than that of natural rocks. Cast iron is suitable for kindling large rooms;
- ceramic cores: inexpensive material obtained by sintering mixtures with white clay, animal bones, feldspar and quartz.