Hi, now to blocking undercuts. After producing our own secondary cast we had to block the undercuts of the cast. The main purpose for this is to make sure when we reproduce the cast using a different stone which is die, the mould produced won't tear and ruined the negative impression. Because the next step to working cast is to produce a die cast where we will place all the wax components of the cobalt chrome. And next to that is the burnout process where we burn out the wax component out of the die. So these are the crucial steps of making a full cobalt chrome frame work.
Anyway, going back to the first process. We used this modelling wax to block the undercuts. And piece of modelling clay to the anterior teeth where there were severe undercuts. So it required something bigger than just a wax to block it.
Blocking the undercut was kinda easy but the hard part for me would be removing the excess using a chisel on a surveyor. Difficult for me to manoeuvre the handle where the chisel is held - it was going all over the place.
Then after blocking everything we free the saddle area by putting in a wax. There were this stipple wax and it was green and very very thin. You place it on saddle areas so that you'd create space for the cobalt chrome and making sure when we add on acrylic, it would cover the entire cobalt chrome.
|There you can see the stipple wax. It's very thin. And I made a square hole to provide a stopper for the cobalt chrome later on. And remember to first draw the outline before placing the components.|
So these are the steps for now. Later would be to duplicate the cast using another type of stone. It's a die stone which would be very hard and can widthstand very high temperature up to thousands of degrees celsius.
Okay that's all for now. Thank you!