Docs Casting Plaster

A Small Selection Of Metals

2010-11-17T08:24:00.000-08:00

A few of our alloys pictured so you have a chance to see what the alloys look like next to the 24kt gold. Unfortunately monitors do vary, but this will give you a very good idea of what the colors are like. This is just a small sample of the varieties avaialble.

Casting 14kw NRH

2010-06-20T10:40:00.000-07:00

Casting our best 14k white gold, a nickel based alloy. Hydrogen/Oxygen torch and an open vacuum casting machine. A very inexpensive easy to use setup.

GIA Tour

2010-04-12T10:00:00.000-07:00

Some of the group.

A close up of hydrogen as a fuel for smelting gold

2010-04-10T19:35:00.000-07:00

A few images shot at our shop on GIA open house day. Once a year we have GIA students in through their alumni programs. The top picture shows the actual smelting of pure gold. Next is a shot of the gold being mixed with the alloy to make it into 18kt white gold. The next shot is that gold being vacuum cast. At bottom the raw 18kt white gold castings.

The advantage of hydrogen for silver, gold and platinum is incredibly clean heat. 5000+ degrees Fahrenheit. Since hydrogen is an element as is oxygen, there is no carbon in the combustion as with natural gas, propane and acetylene. This illustrates how clean our environment could be if our primary fuel were hydrogen. The byproduct is pure water. One great precious metal that responds badly to hydrogen is palladium and palladium white gold.

Resin Cad Cam or Photopolymers

2010-03-23T14:16:00.000-07:00

For those most difficult resin Cad-Cam models...

If you are using this material to simply overcome the defects that you encounter from the use of carving or RP waxes, you can just as well use a normal jewelry burnout cycle in the same oven as your normal daily production flasks.

Method B: (Smaller flasks or small flask-less castings)

Note: Casting flask-less is ideal with this type of material

· Program your oven controller for a ramp rate from 4 degrees per minute to a maximum of 10 degrees per minute. This investment material is very resistant to shock so your ramp up speed can be faster than with gypsum-bonded investment.

· About 1 hour after investing, put the flask into an oven that is preheated to about 300^oF (150^oC), with the wax button facing down.

· Ramp directly up to your top burnout temperature of about 1350^oF - 1600^oF, depending on the metal you are burning out. For photopolymer (Invision or resin based) use the 1600 degree peak temperature

· Hold your top temperature for 2 – 8 hours depending on the amount of material in the flask and the ending top temperature of your flasks. Lower top temps and higher wax content require a longer top temperature dwell times and higher top temperatures and lower wax content require shorter top temperature dwell times.

· It is always a good idea to flip the flasks over around 1200^oF in order to allow combustion gases to escape the mold but is not necessary for longer burnouts.

· Your final flask casting temperature will vary and depends on the type of metal that you choose and the design of your parts.

· Quenching this material will not cause the investment to break away from your castings. This step is done at the appropriate time to give the maximum benefit to your metal crystal structure. You will then need to break away the investment using a hammer or a high-pressure water blast cabinet.

Our Finest White Gold

2009-09-21T10:45:00.001-07:00

Announcing NRh or “No Rhodium” White Gold

The search for improved white gold never stops at PMWest. We are pleased to release our latest White Golds in 14kt & 18kt or White Master Alloy.

PMWest has been working on this white gold for over a year. Taking full advantage of the very latest metallurgical research and development-Precious Metals West announces availability of this breakthrough nickel white gold material for the custom fine jeweler or karat gold manufacturer.

This white gold will not ever require rhodium plating. This is an important cost savings both now and later. This is a gold you can cast yourself, rather than sending it out like you might be doing for Palladium white gold or platinum family metals including palladium.

A few technical points about PMWest’s NRh, or “No Rhodium White Gold”.

These white golds will torch or induction cast via vacuum or spin casting. The resulting button can be re cast or used for fabrication. This is a white gold that is perfectly reasonable to set, engrave or bend and manipulate for forming.

The preferred casting temperature for 14kt using NRh is 1140 Centigrade or 2084 Fahrenheit. Relatively high flask temperatures of 1100F or higher are suggested for all but heavy items. Rhodium is not needed! All the great color with none of the drawbacks.

Watch for more information to be released soon! Contact us vie email or our toll free line for pricing and other details.

Tuning Your Alloy For Ideal Gold

2009-09-09T09:12:00.000-07:00

Tuning Your Gold

Have you listened to the difference the fine tuning makes in a good guitar or piano? Sure they might play alright almost regardless of the fine tuning. But for that wonderful harmony of strings we must have that last 1% of the tuning just right.

Like musical instruments alloy formulae can go back a thousand years and be just a few common metals. Or, they can be from today’s modern metallurgical wisdom. All create wonderful jewelry each and every day. It’s the match of method and alloy additives that makes for success.

O2
Oxygen is life to you, yet destructive to hot gold alloys.
Oxidation is the enemy of fine casting. It is to be avoided when possible and must be removed as best as possible to make the great pieces that sell well. This is the first motive to use additives at all.

Si
Silicon (and other deoxidizers) can benefit casting.
For those who cast 10kt or 14kt in ‘open air” with a torch or electric smelter that exposes the melt to the air, be sure to get an alloy that includes silicon or some deoxidizer. This gives you gold that beaks out less dark, less oxidized, and will re cast from sprue metal reliably. Here is why-When copper is hot it reacts with oxygen from the air easily. So for open air casting some clever alloy people learned to add silicon to the alloy. Silicon additives help because of the blocking effect on the copper oxygen chemistry. Remember copper is usually the highest metallic content in alloy next to the gold. In low karats or rose colors copper content can exceed the gold content. Silicon as a copper “deox” is great for torch casting, but it can cause enlargement problems in grain structure of the castings. That can mean brittle castings. This became the gold standard for years and years. These alloys are very common in the inventories of alloy dealers.
Bullet -Here is where silicon will impede your production.

a. The aforementioned larger grain size can be a problem for fabricators who mistakenly use casting gold for rolling. Fabrication process do not need deoxidation. Pickling after annealing and polishing take care of that.
b. Stone in place castings are brittle because they are cooled slowly rather than quenched. This along with the silicon encourages grain size growth.
c. Eighteen karat gold in general should not contain silicon. There is so little copper, the benefits are outweighed by the risks of brittle casting.

Sometimes a caster with very modern equipment needs a different, non silicon alloy-Alloys for closed system induction are different than the rest.

Beyond deoxidizing

Additives do many subtle jobs. Grain refining is how we manipulate grain size usually trying to get it smaller. This is done with high temperature exotic elements. Fluidity and casting flow temperature can be adjusted with additives. Some ordinary materials like zinc, sometimes very exotic stuff like lithium.

Electric casting with some form of atmosphere control like nitrogen or argon in the crucible during heating and casting is common at larger jewelry factories. This technology was originally so promising some companies tried to use unaltered ancient alloy formulas-Just pure gold, copper and silver without any additives. While these alloys avoided the pitfalls of silicon sticking in the newer “bottom pour” electric casting machinery, they were not ‘tuned’ for the new machines. As it turned out certain gas reactions with the investment plaster also prevented the best possible results. This taught us that additives do help a great deal. They always will when applied correctly.

Today’s demanding market sees casters using all kinds of equipment. On one hand we have casting machines that completely isolate the metal from air with exotic gases or a vacuum. Those use resistance or induction for heat. The method varies, but the one thing in common is that air need not get to our gold anywhere near molten temperatures. So, we tune alloys accordingly.

Alloys and casting harmonies-It’s an orchestra like any other. Nobody can be out of tune!
Your alloy maker’s job is to match your alloy to your process. Not just casting, stamping or fabricating, but one must precisely see what equipment is being used. You might use alloys adjusted for “pressure over vacuum” vertical casting systems. Each kind calls for certain alloy tuning.

Karat your gold before casting.
Be sure to blend your gold and alloy, pour it into shot, and only then re-melt for casting. This assure consistent color and karat through the tree. This prevents several potential problems with just a small amount of extra effort

Learn to raise and lower karat in your trees and sprue metal.
Many alloys can be useful in two karats or more. Consider using 1oky sprues by up karating with gold, using some fresh 14kt and casting on less gold overall.

Your Alloy maker as your Metallurgical Guide
Metallurgy is a complex and often counterintuitive science that frankly only a practicing metallurgist can love. Let that person be your guide to enhanced quality in your production. His or her knowledge can save you hours of work and thousands of dollars.

Have confidence in metallurgy, never allow alloy oddities to confuse you.
Today’s most modern alloys are 99% just like the alloys we always could depend on. Gold, silver, copper etc. However, that last 1% makes all the difference in reliable casting. As we use ancient precious metals, we can now use up to the minute technology in that crucial; last, 1% or the gold. That last one percent can contain many additives that make an important difference. These differences include grain structure, ease of filling in small items, hardness, and trapping nickel into the alloy so tightly as to pass certain restrictions abroad.

In the best scenario, your alloy is custom tuned. Not merely adjusted for your equipment but also adjusted further, for whatever you are particular line calls for. Tiny items can be cast with alloys that are far from ideal in larger items like mans rings. More or less hardness as needed. Color tuning for that special look. All of this is very likely in the modern alloy market. Your alloy maker can give your casting gold exactly the tune up you need. Make the call. Send the email. You will be glad you did.

Summer Relief For Bench Jewelers!

2009-07-24T13:16:00.000-07:00

We know how difficult being a bench jeweler for a retail store can be. Whether you work in house or from a central shop, we want to help. From now until labor day, any bench jeweler can try a sample of our plumb solder at no cost. Just contact us via email and Daniel will contact you to arrange a free sample of any cadmium free plumb solder, in Gold, Palladium, or Platinum. We have the lowest flow plumb gold in the business. We invented the famous patented plumb platinum solders. We had the very first 950 palladium solders. This offer ends labor day!

Short on cash or working gold? Send your useless scrap or filings for fast money, gold, or any product we offer at the best possible price.

Removing or Devesting Docs

2009-06-02T13:20:00.000-07:00

Platinum Investment Removers & DOCS

Sodium Hydroxide Powder-"Drano"

We suggest you use a small container 3% hydrogen peroxide and dissolved Drano powder. Place the container on a wire rack in your heated ultrasonic cleaning machine.

Caustic soda and caustic potassium solutions are also used by some casters. We suggest that hydrofluoric acid not ever be used, as it is a painfully, lethally dangerous acid.

Casting Diamonds Into Platinum "Stone In Place"

2009-05-27T14:38:00.000-07:00

Sometimes we are asked about a trick we pulled off years ago to prove how good Docs really is. Okay here goes-Assuming injection wax only, and you will be casting diamonds "stone in place" very little changes. Put he diamonds in the wax just as you would in metal. Be sure to use decent diamonds, certain extensive flaws will lead to breakage. Do be neat-no sloppy wax work allowed. No special alloy is required-Just use 95/5 platinum.

You will keep the "burnout" down to 850 or 900 degrees F! This will hopefully avoid damaging the diamonds with excessive heat such as a 1300 degree burnout. That kind of heat will ruin any stone let alone diamonds. Some folks are brave enough to try this with other stones such as sapphire, but we make no guarantees here. So you keep the oven at 900 F and hold that long enough for all the wax to burn out. This is at least six hours.

Then you remove the flask, let it cool to 500F and cast as per usual. I have posted a picture or two from when we did this at our shop.

Getting finning on photopolymers?

2009-05-13T11:13:00.000-07:00

One good fix for this is use a 1,600 degree burnout rather than the suggested 1250. Docs will fuse into a far stronger material and withstand the expansion pressure presented by resin models. Thanks to Manuel Novo for this tip which came from a new ultra smooth product from Envision. The new material is a kind of orange color and is very highly detailed. The picture is just a good casting done in Docs and 95oPd.

New Instruction set for Docs

2009-05-12T15:33:00.000-07:00

Fine tuned and re-written with actual uses in mind. Tell me what you think! The instructions are at the bottom of the blog.

Purple gold casting experiment

2009-05-11T14:17:00.000-07:00

Jewelers and casters are not often big time bloggers. But, hey this is for you. If you have a question or a comment on Docs, casting, metals or whatever ails your castings. You can post by name or anonymously.

What do you think of that purple?

Docs Casters Blog

2009-05-11T09:47:00.000-07:00

Docs is a high speed and high temperature casting investment plaster. This is the material that literally revolutionized platinum casting back in the 1990's. The materials high strength and very low platinum flask temperature improves results at almost any casting shop.

When a 1600 degree burnout is used, it is capable of withstanding the most demanding model materials like high resolution resins from Cad Cam operations. This is whee we keep instructions and tips on using Docs-written by us here at PMWest or posted by you-the users.

Docs what you use for white gold, palladium white gold, 950 palladium or of course any platinum alloy. If you are in need of "same day" casting our three hour wax to cast cycle will save your deadlines.