We know that time is money in today’s modern dental lab.
Our aim is to get you answers to your questions as quickly as possible.

Shenpaz Resource Center – Training and Troubleshooting

To save you valuable time, we have posted here our library of basic training and troubleshooting resources here.
Don’t hesitate to contact your local dealer or contact us if you don’t find answers to your questions on this page.


Sintra Zirconia Sintering Furnaces

Horizon Ceramic Firing & Pressing Furnaces

Gemini Furnaces Ceramic Firing & Pressing Furnaces

Focus 4010 Porcelain Firing & Glazing Furnaces

Focus 4010 HT Porcelain Firing & Glazing Furnaces

Blazir Zirconia Sintering Furnace


Click on a symptom to see the possible cause and suggested solution.


Porosities, cavities or fractures in the metal framework
Sprucing recommendation by manufacturers or recommendations on pre-heating and casting temperatures were overlooked. Check manufacturer request for casing metal and investment.
Ceramic shades are too bright and too opaque
Preheating temperature is set too high. Decrease preheating temperature.


Ceramic material is too porous
Firing temperature is too low. Increase firing temperature.
Vacuum pump was actuated too late. Decrease preheating or vacuum temperature.
Attained vacuum value is too low. Check vacuum pump for leaks.
Ceramic surface too rough.
Firing temperature too low. Increase firing temperature.
Ceramic surface has too little luster.
Holding time too short. Extend holding time.
Ceramic surface has too much luster.
Firing temperature is too high. Decrease firing temperature.
Edges and contours are not clearly defined but round.
Holding time is too long. Shorten holding time.
Cracks caused by compression: horizontal cracks in the incisal region or in the bridge pontic
Extend cooling required by manufacturer of ceramic or metal but was not implemented. Check CTE of the alloy/use 3 minutes at 850C°; cooling required if CTE > 14.2 (standard)
Cooling temperature is too low. Increase cooling time.
Cooling temperature too short. Extend cooling duration/phase.
Cracks caused by tension
Incorrect alloy used. Check alloy compatibility (CTE).
Crack in ceramic surface
Ceramic CTE is too high due to extended cooling or low heat rate or framework wall is too thin. Respect wall thickness and check CTE of CERAMIC and cooling instructions per manufacturer.
Bubbles appear
Metal or ceramic impurities caused by use of improper grinding instruments. Use only tools specifically designed for metals and ceramics; use only stagger toothed tungsten- carbide cutlers
Paste opaques did not dry correctly. Extend predrying phase according to manufacturer's instructions.
Entrapped Air. Extend predrying phase according to manufacturer's instructions.
Too much opaque thinner. Extend predrying phase according to manufacturer's instructions.
Paste opaque applied too thickly Will require ceramic rework.


The object is not completely pressed
Insufficient material quantity. Calculate weight of wax including sprues to determine the number of ceramic ingots.
Wax layer is too thin. Minimum wax layer should be 0.5 mm.
Press temperature is too low. Slowly increase temperature to find ingot melting point. This will vary between different furnaces so this should be adjusted by trial and error.
Press time too short. Increase pressing time.
Press pressure too low. 4.5 Bar for 1x and up to 5.5 Bar for 2x.
Press streaks on the margins of crown
Incorrect sprueing. Inlays with margin should be facing to the outside and at the same height; also minimum of 3 mm sprue and as short as possible.
Press steaks on wax objects and the press sprues
Crack in the investment materials. Adhere to the working instructions, observe setting time and correct ratio of water and liquid.
Burst investment ring after pressing
Ring is not parallel to the plunger. Pressure or temperature is too high or insufficient wall of the investment. Check parallelism of the cylinder. Check program parameters and keep 10mm from the border of the cylinder.
Crack in the press ceramics
Incorrect procedure with ZR. Use suitable tool for working on ZR.
Over heating in some area of the press ceramic during processing. Decrease temperature and increase preheat.
Excessive blasting during devestment. Sandblast, 50 micron at max 2 Bar.
Wax did not totally burn off. Use wax adapted to pressing system.
Incorrect sprueing. Ensure correct sprueing.
Bubbles in the press ceramics
Press temperature too high. Reduce press temperature.
Wax didn't totally burn off. Change wax to one adapted to pressables.
ZR was not cleaned correctly before waxing. Clean ZR before waxing.
Inclusion of investment into the press element
Sprues were not waxed properly. Ensure smooth transition of short and big sprues.
Edges are too sharp. Ensure smooth transition of short and big sprues.
Discoloration and white spot
Press temperature is too high. Try with lower temperature for a longer time.
Check wax bonder or liner. Use only products adapted for top press systems.