Thermal mud is a special mixture formed of a claylike solid component, a liquid component (thermal water of different composition) and an organic component that mainly forms during the maturation period. Before the thirties clay was considered an amorphous and colloidal substance, while modern mineralogical methods have made it possible to highlight its most important components: the claylike minerals.

The discovery of said minerals surely made for a better understanding of the mud's ‘maturation process’ which lasts from 1 to 2 years. An enrichment of vegetable and animal micro-organic substances occurs during this process and at the same time the various fractions that make up the mud become more closely mixed. According to their special structure, thermal muds act in a curative manner through specific stimuli – heat action, mechanical stress and physical-chemical and chemical action.

As far as the heat component is concerned, there is no other substance quite l ike mud which has the physical and physical-chemical properties needed to generate so much heat and slowly release it on the section covered in mud without causing any inconvenience.

The mud used can be natural (i.e. mud as it is found in nature without any subsequent modification or addition of substances) or artificial where specific processes are used to decide the mud’s chemical components and properties.

Mud packs using thermal mud created by combining the solid component (claylike) and liquid component obtained from the springs are particularly suitable for treating dermatological, arthro-rheumatic (osteoarthritis) and locomotion problems, gout and also gynaecological complaints using a particular method of applying mud directly to the pelvis area in the form of ‘underwear’.

The solid and liquid components of the mud used, their chemical composition and their organic and inorganic characteristics can vary considerably which leads to a great selection of muds.

In muds , the liquid component can also be seawater while the solid component consists of mainly mineral components which generally come from the floors of lakes or lagoons or from the accumulation of detritus on the riverbed.

In peat, (which also come mainly from lakes or marshes) there is also a significant organic component due to the slow transformation process of the vegetable organisms which produced the peat.

Mildews (the use of which at the Vinadio and Valdieri thermal spas is well-known) result from a combination of water (mainly sulphurous) with a solid component with a base of algae or other organic marine components.

Fangotherapy is practised in many Italian spas and there is a particular tradition in the Euganei Hills (Abano and Montegrotto) where application of a mud pack is followed by bathing, a perspiratory reaction and a massage session. These are four successive stages, each of which is important for obtaining all the benefits from a thermal treatment session. A particu lar type of fangotherapy is performed at Recoaro which uses ochre mud. This is the natural deposit that forms in tanks with water containing iron and is of a distinctive colour. It is particularly suitable for treating degenerative and post-traumatic arthropathy and fractures.