“The Ion Sponge”
Purge-all and Purge-all plus
Maintaining a clean porcelain furnace is paramount, when processing today’s fine grain porcelains. For years we have been told to purge our furnaces with carbon, but what exactly are we doing? Unfortunately we have not been very well informed about carbon as a “purge” material.
Carbon comes in various qualities or grades, from the likes of charcoal to the highly activated carbons used in various industries mainly to eliminate contaminates, it is true that if you use a highly activated carbon in your furnace at a low temperature it will absorb silver ions.
We have been taught to take carbon to very high temperatures and this will clean our furnaces. This is not correct, in fact by doing this we actually ash the carbon in the furnace and release Cr, Si, Cd, etc. this is just the opposite of what we want to do.
The need for something better was apparent, especially with the use of all the various metal chemistry we use in today’s dental market.
Purge-all and Purge-all plus is the culmination of almost 2 years of research with Carbon engineers and scientist on vapor phase absorption chemistry. This material is literally an ion sponge; it is highly activated and absorbs specific ions that are shed in the oxidizing process of cast metals.
Purge-all absorbs specifically, Ag, Pb, Cu, and Co.
It comes in the form of granules a brown and white mix. It has a pore size of 4.1x 3.7 angstroms with a cavity size of 11.0 x 6.6 angstroms. The total pore volume is .468 cm3/g. The ion exchange capacity is 2.50 meg/g
Purge all-plus absorbs specifically the following ions, Rb, Na, Ba, Mg, Li, Sr, Fe, K, Cd, Ca, Al, Nb, Zn, Hg, Cr, C, and Be. Not that we have all the ions in the metals we use, but we do have several of them. This material too comes in granules, white with a pore diameter of 4.0 angstroms and a pore volume of 15%. The specific surface area is 40m2/g with an ion exchange capacity of 1.65 meg/g
These are non-toxic materials and are not reusable. This material will also eliminate odors from your furnace from various materials. For those using Captek or Sinter-Cor this material will absorb carbon from the muffle from the wax elimination process.
These materials are used at a relatively low temperature, around 700 degrees Celsius and the slower the material is cooled the more ions it will absorb.
In today’s complex restorative materials market place we must have clean furnaces to make the most of the porcelains and other materials that we use. Purge-all and Purge-all plus gives us an advantage in that process.
Rich Pavlak CDT, MDT, TFNGS