HERE WE GO!
Lithium disilicate melts at 885C. to achieve this meting temperature inside the ring, the typical program rases to a hold temperature higher than that of the melting temperature. This all has to do with the thermal mass of the object the energy is being put into.
A strait line heat thus causes the inside of the ring to have a temperature lower than that of the outside of the ring. This causes the material to press to a temperature much higher than that of the insdide of the ring, thus overheating the material and causing it to append itself to the investment it is pressed to. This causes the reaction layer everyone hates. This is why you pay for and have to use an acid bath.
The optimal pressing situation is to have the inside of the ring, outside of the ring and chamber all at the same temperature when it is time to press. In order to achieve this environment, the firing perameters have to be changed to accomidate the thermal mass of the investment and material.
That being said the normal rate rise to a hold temperature that you press to will not work.
Our system raises the heat and then drops it so that when we press ALL the temperatures are the same, thus not overheating the lithium disilicate and providing the optimal environment. May I now add that this allows for a reaction layer free pressing, saving you 3/4 of the time you spend on processing a unit. approximately 1/2 the oven processing time, no time in an acid bath. Which also saves you money on acid!
The way we process the Lithium disilicate does not negatively affect the properties of the lithium disilicate in any way. The process merely changes the firing perameters to actually accomidate the thermal mass.
Our brochure which is available online will more specifically explain the actual temperatures I am referring to. below is the brochure link.
http://www.zubler.de/files/m_vp300e_en_110209.pdf Chris