Stone/Water Ratio: How important is it?

[BruceQuality]

In your experience, how important have you found the stone to water ratio to be for the fit of crowns?

We pour two models for every case, a working model for the master die and a second pour "solid" model to check contacts.

I've found inconsistencies with the models such as contact areas and/or margins being more easily scraped on the master model to "solid" models being so deformed that they are unusable.

Our model department does not weigh/measure stone/water when pouring...

So I am now questioning if these inconsistencies could be because of inconsistent stone/water mix?

Thank you!

 

[TheLabGuy]

I've found inconsistencies with the models such as contact areas and/or margins being more easily scraped on the master model to "solid" models being so deformed that they are unusable.

You answered your own question.........

Personally, it's very important, like I've stated before, I've seen labs lose accounts over this.......at the very least this is what I do, I have my model folks measure out and mix according to manufacturer's instructions one day a week so they never forget the viscosity of the mixture of what it should be like. I know it's a pain in the backside for them, but you know what, I won't lose accounts over it. Over time we get lazy and forget what the mixture should be like and soon it has way to much water or not enough.

 

[Al.]

Sometimes the second pours are not good because of distortion from seperating the moldels and the material tearing.

But as far as measuring the stone and water it is very very important.

But to do it buy hand is way too time consuming and I would not trust employees to do it consistantly.

I have both the Smart Box and the Whip Mix Aqua Spense.
Well worth the money !!!!!!!

But buy the Aqua Spense, it is half the price and more dependable because of less working parts.

You put your stone in the mixing bowl and it weighs it and despenses the water into your bowl.

The Smart Box will add both stone and water to your bowl so it is quicker to use but the worm gear that despenses the stone can have issues. It has bearings that can go and the gear can clog if you use fine stone, plus it is a pain to fill with stone. Not to mention the 5 grand price tag and parts take forever to get from Germany.

The Whip Mix Aqua Spense is the way to go and I think you can get it for under 2 gran.

 

[JohnWilson]

Sometimes the second pours are not good because of distortion from seperating the moldels and the material tearing.

But as far as measuring the stone and water it is very very important.

But to do it buy hand is way too time consuming and I would not trust employees to do it consistantly.

I have both the Smart Box and the Whip Mix Aqua Spense.
Well worth the money !!!!!!!

But buy the Aqua Spense, it is half the price and more dependable because of less working parts.

You put your stone in the mixing bowl and it weighs it and despenses the water into your bowl.

The Smart Box will add both stone and water to your bowl so it is quicker to use but the worm gear that despenses the stone can have issues. It has bearings that can go and the gear can clog if you use fine stone, plus it is a pain to fill with stone. Not to mention the 5 grand price tag and parts take forever to get from Germany.

The Whip Mix Aqua Spense is the way to go and I think you can get it for under 2 gran.

I second the recommendation for Whipmix, I have both the water and the special liquid dispenser and it brings consistency to a very inconsistent department.

 

[2thm8kr]

I use a triple beam balance and specimen cups. (New of course).
Less than 100 bucks

 

[BruceQuality]

Thanks guys! You also answered further questions for me on equipment and options, so the advice is well received!

Thank you!