Anyone know the ratio of resin to gold or silver?

[noahbern]

Hi,

Anyone know what a cured resin ratio to gold or silver?
Thanks

[noahbern]

I just realized I have a resin ring and complete one
one ring in YG it weighs 3.1 dwt
the resin ring weighs .3 dwt.....
I am doing another casting but I think its around 10.0 for YG 14K
What do you guys think?

[afholderman]

Apparently you and I at the same stage in the game! I asked the same question earlier today. Check out the submission right below yours entitled "What is the specific gravity of the fully cured resin?" for what we've come up with this far.

[santanagoldworks]

Here is the standard casting procedure : wax to metal ratio. All these will be in grams. 1 gram wax in 14k = 14 grs in metal. then for silver will be 1 gram of wax= 10 grs of silver. Keep in mind and depending on the casting equiptment you need an extra 10 grs at least for sprue and button.

[lswatson]

I've been told that the resin and carving wax are about the same for that calculation.
I have not checked that out, even though I've had some resin models cast.
RhinoGold has a conversion utility that I hope someone will check out.
I have a version that is about 2+ years old.
I need to get the update. It also has an analysis option to show where to put supports.
And a great support build tool.

[noahbern]

ok this is from mike ;


Our resin is approximately 1.1 grams per ml.



Gold is about 19.32 grams per ml.

The volume of the print in ml (of resin or any material really) is estimated in the Print dialog, just multiply that amount by 19.32 to get the estimated grams of gold in the print.

Or you could weigh the actual item and divide by 1.1 to get the estimated volume in ml. Then multiply that number by 19.32.

Or you could weigh the actual item and multiply by the resin to gold ratio (19.32/1.1 = 17.56) to get the estimated gold required in grams.

So, I think the answer the students are looking for is 17.56 grams gold per gram resin. :-)

But I wanted to point out that they can estimate the amount of gold by looking at the item's job file in the Print dialog.

[mikej]

Your actual measurements are probably more accurate than my estimates above...

[noahbern]

Oh good to know so where back to resin x 10 = YG casting number

Anyone else

[noahbern]

Don't listen to that last bit about the resin x 10 ... I did another casting and should know in a little while

[Robert Howle]

This is about 35 yrs old. Notice the discoloration. This is from a book on metallurgy. I have been using these since my factory days. I know that some of the alloys used today may change some of the values only slightly (just round off if u feel the need, I don,t_ Click on these to enlarge. Just use the specific gravity. Wax has same SG as water so just multiply wax equivalent x SG of chosen metal.

[afholderman]

Alright from the other thread concerning specific gravity it has been determined that the resin's SG is equal to right around 1.1. I am drawing this conclusion from the pre cure specific gravity (listed on the MSDS as 1.10-1.25) and the fact that cured resin still sinks in distilled water (specific gravity of 1). Previous jeweler's formula for determining approximate cast weight used 1 as the specific gravity for modeling and carving wax. That meant that all you needed to do was multiply your wax weight by the specific gravity of the desired precious metal (See Robert Howle post above). With a slight change in specific gravity the new formula I have worked out looks like this:

(x*y)/1.1=z

x= Resin model weight
y= Target metal specific gravity
z= Final weight in metal

If you are sending it out to be cast like me then this will give you a good estimate of final cost. I you are going to be casting yourself you can then you probably will be okay with just using the same formula. By the time you get done calculating buttons and sprues the difference will be negligible for single castings.

[Robert Howle]

Weight of model (divided by) 1.1 x S.G. of metal to be used = metal weight estimate

Example: Model weights .5 grams (divided by 1.1 specific gravity of resin) = .45 grams .45 x 13.07 (SG of 14k yellow gold) = 5.88 grams 14k yg

Not preaching here, just showing how basic this is. Not aimed at the jewelry casters here, just individuals that don't have casting experience.

Keep in mind when using the metal list above that melting pt. temps and flow pt. temps are not the same. When heating for casting you want to go past melt to flow, but not to swelling of the melted metal (If u go to far, especially on heavier items, you will get shrinkage porosity. Don't know if this applies to other metals, I am only familiar with the precious metals.

[afholderman]

Quote from Robert Howle on August 15, 2013, 12:21
Weight of model x 1.1 x S.G. of metal to be used = metal weight estimate

I don't believe this formula is correct. The weight of the model in cured resin already factors in the specific gravity of 1.1. By multiplying it a second time you are increasing the effect of specific gravity. That is why I divided by 1.1, to get back to an amount equal to the specific gravity of modeling wax. This is because if you have identical models one in wax and one in cured resin the resin one will weigh heavier due to being more dense, as indicated by the higher specific gravity. So if you were to then multiple the already heavier model's weight by 1.1 you are increasing the gap between a wax estimate and a resin estimate, not reducing it.

[Robert Howle]

Please check my work now. Went back and edited my post above. Thanks for the heads up. Brain f*%t.

[jbin]

Quote from afholderman on August 15, 2013, 13:30

Quote from Robert Howle on August 15, 2013, 12:21
Weight of model x 1.1 x S.G. of metal to be used = metal weight estimate

I don't believe this formula is correct. The weight of the model in cured resin already factors in the specific gravity of 1.1. By multiplying it a second time you are increasing the effect of specific gravity. That is why I divided by 1.1, to get back to an amount equal to the specific gravity of modeling wax. This is because if you have identical models one in wax and one in cured resin the resin one will weigh heavier due to being more dense, as indicated by the higher specific gravity. So if you were to then multiple the already heavier model's weight by 1.1 you are increasing the gap between a wax estimate and a resin estimate, not reducing it.

You are correct, multiplying resin weight by 1.1 times the SG of the target metal will be too much metal.

[akgold]

Weigh your casting model with the sprue and button on it then refigure your weight ratio.
That will give you a multiplier that determines the total metal needed to cast.

I use 15 times the wax weight of all items to be cast in 14k.

[jbin]

You will end up a little heavy on the metal because the resin is heavier than wax.

[marios.jewelry.service@gmail.com]

I checked a wax vs resin model and I've come up with; weight of resin in grams x 9. The math worked out to 8.78. The wax weighed .15g and Red model weighed .227g.

[Robert Howle]

I don't think the issue is comparing an actual model in wax to resin. All that really matters is that the specific gravity of the resin is higher than that of wax. Just weigh your fully cured model, (approx. specific gravity of resin is 1.1) (actual specific gravity of wax is 1.0). subtract 10% then multiply it by the specific gravity of the metal to be used. Add drive weight. Done. See specific gravity chart posted above for all metals u might use. I know it is old but have been using it for nearly 35 years in factory and retail environment. It is accurate.

[ckl81]

Quote from akgold on August 15, 2013, 20:25
Weigh your casting model with the sprue and button on it then refigure your weight ratio.
That will give you a multiplier that determines the total metal needed to cast.

I use 15 times the wax weight of all items to be cast in 14k.

I used the same ratio