Help, new to pressing

TheLabGuy

TheLabGuy

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8min press time for a 100g ring? that might be your issue. or part of it.

what pressing furnace are you using (pardon me if i missed it)?
as stated above, most 100g rings press in 1min10sec-1min45sec here.

your latest pics look far better, though a bit "cold" hence the short press and the glossy look where it pressed short. your initial pics looked to be way scorched and over baked. which is why the major reaction layer is present. i would lean toward something being off in burn out, or pressing, or both.
Increase psi to 67 as well
 
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Drews Dental Lab

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Increase psi to 67 as well
Here is my result after increasing to 865c and increasing to 10 min hold time also with 67 psi

Still a little pitted I don't know if that normal/acceptable and my sprue angle could be better
 

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ztech

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Here is my result after increasing to 865c and increasing to 10 min hold time also with 67 psi

Still a little pitted I don't know if that normal/acceptable and my sprue angle could be better
The pitting is not acceptable. That is the result of the hold at an excessive temp. Increase hold and decrease temp, LiSi recommends a 25 min hold and Emax recommends 15. If you stray far from that, the pits or the result. The temp is variable to the oven the other parameters are not.

On your sprue, place the sprue on or slightly behind the incisal edge to prevent another problem you will otherwise encounter. While pressing the rods of the material align while going through the narrow sprue. Once on the other side, they tumble and mix. This alignment will create a visual anomaly that is like looking through a the end of a glass rod. It will result in a grey circle that is extremely difficult to cover with colorant.
 
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FASTFNGR

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I am new to pressing and I am having an issue with fit and the texture, along with some complete failures.

I am using Microstar investment 20ml expansion liquid to 5ml distilled water with emax and Gc Lisi with same results

I have tried my burn out oven diffrent temps ranging from 1500 to 1600

Pressing oven is set at 70 psi
Microstar is a very good investment but you are running way too high of a pressing temp. If you have an Ivoclar oven, the temp is preset for you. If it is not an Ivoclar oven some testing need to done to get to the right one. Each oven need to be tweaked a bit.
 
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Drews Dental Lab

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The pitting is not acceptable. That is the result of the hold at an excessive temp. Increase hold and decrease temp, LiSi recommends a 25 min hold and Emax recommends 15. If you stray far from that, the pits or the result. The temp is variable to the oven the other parameters are not.

On your sprue, place the sprue on or slightly behind the incisal edge to prevent another problem you will otherwise encounter. While pressing the rods of the material align while going through the narrow sprue. Once on the other side, they tumble and mix. This alignment will create a visual anomaly that is like looking through a the end of a glass rod. It will result in a grey circle that is extremely difficult to cover with colorant.
I changed my hold time to 25 min and this is my result, The glossy areas are from me trying to see how far the pitting went. Fit was good just pitting and rough margins.

Microstar investment

Lisi
Whip mix SP
Conventual Press
700 entry
60 rise
860 hold temp
14 min hold time
8 min press
2 min cool

67 psi
 

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ztech

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I changed my hold time to 25 min and this is my result, The glossy areas are from me trying to see how far the pitting went. Fit was good just pitting and rough margins.

Microstar investment

Lisi
Whip mix SP
Conventual Press
700 entry
60 rise
860 hold temp
14 min hold time
8 min press
2 min cool

67 psi
Now reduce the temp by 5 C to make the fine adjustment. When you get small spots like that, reduce by 2C to get it where it is smooth all over and no voids. Again the goal is to get a complete casting with as little reaction layer as possible. Bubbles equal heat, excessive reaction layer equals time in the mold after pressing and heat. Rounded margins or incomplete pressing is heat saturation at temp and/or not enough temp.
 
KingGhidorah

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Call Lisi, there’s a super nice tech there called like mr. roshi or something? He helped us lock in the right temps and everything to get perfect results with lisi press. He’ll have a bunch of recommendations and will tell you to call after trying those out so he can further dial in what to do.
 
Tayebdental

Tayebdental

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Even though I love Emax and LISI, but I am fabricating less of these restorations and more of PFZ, saving on time imo with excellent results
 
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