Laboratory reagents suppliers in south africa

1. Laboratory reagents suppliers in South Africa
The cataloguecontains products of:
 Ceramic ware
 Glassware
 Plastic ware
 Zirconium ware
 We are suppliers of HALDENWANGER laboratory porcelain.
 Laboratory porcelain has existed for thousands of years and over this time has developed
to the high standard that it is today. The properties of Haldenwanger laboratory porcelain
correspond to DIN VDE 0335 type C110. It has a high resistance against thermal shocks
and against physical and chemical attacks. The constant quality is guaranteed by rigid
control of raw materials and processing.
 Laboratory porcelain is a very acidic potassium-sodium-silicate and is formed by a
network of scorched mullite crystals (3Al2O3.2SiO2) embedded in glass phases. Free
quartz is only present in insignificant quantities in the form of small crystallites with
rounded grains and is surrounded by a glass phase that is rich in SiO2. Because it is an
acidic silicate, Haldenwanger laboratory porcelain is very resistant to acids of all types,
except hydrofluoric acid, even boiling acids. The resistance against warm, highly
concentrated alkaline solutions is lower but still considerably better than that of glass.
 Molten alkali will attack laboratory porcelain. Resistance against high temperatures is
maintained because of the mullite network. The glass phase will soften but the
mullitenetwork acts as a support and hinder deformation.
 Unglazed laboratory porcelain can be used at temperatures above 1400◦C. Glazed
laboratory porcelain can withstand temperatures up to about 1200◦C as this is the
softening point of the glaze.
 When using glazed laboratory porcelain it is easier to completely transfer chemicals from
one vessel into another. Furthermore a “suitable” glaze will improve the resistance
against thermal shocks. Thermal expansion of Haldenwanger laboratory porcelain is low
and has a linear behaviour ove the whole range of operating temperatures. Laboratory
porcelain ware can be cleaned by scalding them with concentrated acids that will not
affect their usability so that they may be re-used immediately. Care should be taken
when scalding crucibles that have porous bottoms with hot concentrated lies as the
bottom might be attacked.