OK, lots going on here. Silicone is a good idea. I use Zhermack double elite. Use a debubblizer and lightly air dry just before carefully pouring. DO NOT use die stone! Die stone is for................................
DIES!
lol. Use type 3 stone for the duplicate model ( the stone that most labs call lab stone or yellow stone, model stone, etc) if no vacuum mixer, ok, just vibrate good to make as dense as possible, and you could put into a pressure pot for 20-30 minutes while it sets. I've never known a lab without a vacuum mixer-either an in house lab or regular dental lab. Basic equipment. BUT, these days, a lab without a vacuum mixer is a digital lab......and yours isn't! Just get a vacuum mixer, lol. The reason why you are to use type 3 stone is that it has give. Type 4 die stone is very hard, for a reason, and brittle. The bar is bulky in my opinion. My concern is the bar extensions past the distal locators. I don't like the angles, and what is the distance past the distal implants? If you're more than 15mm, I'd be concerned for sure, 12mm would be safer. I use ivocap which is similar to Ivobase. Yes, always do a wax up and try in BEFORE fabricating bar. This way the bar manufacturer can scan the denture, and design the bar within the confines of the denture. You should ask to see the design before milling as well, so that you can visualize what you are getting back. If you don't like the design, that is the time to ask kindly for changes. That gets done, you have a looksie again, if more changes need to be made, you ask for more changes until you are satisfied. And, I wouldn't say that the bar is bad, I just see areas that I would want differently, but just like I am giving you instructions and opinions here, another tech likely has a different technique and opinions to mine. The other thing that I like to do is send manufacturer files to the prescribing doctor and bring them in to the loop so that they see what is being fabricated. I only work with prosthodontists that do this kind of work, and they are pretty knowledgable and have a keen eye. Don't stuff the holes full of lab putty! PITA to clean out. If you have round wire casting wax, like 10 or 12 gauge, put a piece of that in the hole almost to the top then use a bit of putty that you can just flick out when you're ready. I just flash over the holes with wax and steam afterwards. Easy breezy. And other undercuts, I still prefer wax-its slower, yes, its what I work with, but I've been in the field probably longer than you have been alive, hahaha. You can certainly use lab putty, its not a way that I have done it.