by Glenn Klein
1. Drill a one-quarter inch hole in the jaws of a wood clothespin. The clothespin will hold the hot metal dop.
2. Dip the metal dop into a small jar of clean alcohol, and wipe the dop with a clean tissue (I use Kimwipes which have less lint).
3. Using a tweezers, dip the gemstone into the clean alcohol, and wipe the gem with another Kimwipe tissue. Be sure to wipe the area of the gem that is to attach to the dop. Do not touch that spot with your fingers until dopping is complete. Fingers always leave an oily film.
4. Heat the metal dop in the flame of an alcohol lamp. Heat the dop sides as you turn the dop often. This gives even heating to the dop. Do not stick the tip of the dop into the flame. The flame tip will have bond-loosening carbon, so use the heart of the flame.
5. Begin to stick the hot dop into the bar of wax (I use green dopping wax). If the dop is not yet hot enough, heat it some more.
6. Try to get as much wax on the dop tip and near the tip as possible.
7. When the dop is as full of wax as you can get it, apply the dop to the gem. Hold the gem below the dop. Hold the gem firmly to the dop, and maybe, turn the dop a bit so that you are sure of a firm contract. We are just trying to get wax onto the gem, and to get the gem warmed up. Do not pre-heat the gem itself in any other way. As the dop begins to cool, pull the dop away from the gem, and try to apply the wax that is remaining on the sides of the dop onto the gem. We are trying to build up a little extra wax there. The gem will get warm/hot in your fingers.
8. Now re-heat the dop, and again get as much wax on the tip as you can.
9. Apply the dop to the gem with the idea that this time is the final time. Before we just wanted to get the gem warmed up, and also have a sufficient amount of wax available for a good bonding. Try to swing the gem up so that it is above the dop. This time, be sure the dop is centered in the area that you want attached. You will be pretty accurate by just eyeballing it. There should now be a sufficient amount of wax tapering off around the gem to help with getting a good bond.
10. Let the dop and gem cool by using just the air in the room. Give it plenty of time. Do not stick the dop into water, or use a wet tissue over the gem. That would shock some gem materials. You could have a hunk of iron with a hole drilled into it, just large enough to support the dop with its gem above. The iron would serve as a heat sink, and would drain off the heat from the gem down through the bottom of the metal dop. If you force cooling more drastically, you often will find that you do not have a good bond.
11. Depending on the size of the dop and gem, I sometimes lick my thumb and index finger, and then quickly press the extra wax more evenly around the bonding point. This has to be done while the wax is still very hot. Otherwise, you will weaken the bond. Once the whole thing has cooled a bit, it is too late to make any adjustments. If you were to move the joint, you would have a “Cold Dop” result, a poor bonding.
12. The procedure that I have called out above is especially important if you are using small pieces of gem material (like the under 3mm stone required in an AFMS competition case), or materials which have a great sensitivity towards heat.
13. SOME NOTES: I do not pre-heat gems. I have never used glues to attach dops. I have never liked the idea of coating the gem with Shellac before dopping, which our fearless leader Glenn Vargas suggested that I try…some twenty years ago. My gem never gets directly into the alcohol flame. I do not use any wax that has been in the flame. I do not reuse any wax. Burnt wax would have had some of its ingredients removed, making for a poor bonding.
Now for the Transfer Procedure
14. There are a variety of transfer jigs available. Mine came with my Ultra-Tec back in the seventies. I think it is as good as any of the others I have seen. One side of the jig is a larger piece of metal…it is a heatsink. It is there to keep the original dop and its attached gem cool. The piece of metal on the other side is smaller, and is meant to be heated. It will hold the new dop to the previously faceted pavilion of the cut design.
15. Dip the dop with the attached gem into the clean alcohol, just to where it is near the girdle of the cut. Wipe the pavilion with the tissue. Do not soak the original bond entirely into the alcohol because that would weaken it before the transfer is complete. The alcohol initially used and also used now should be from a small jar, which is meant for this bonding procedure only. It is to be unpolluted alcohol. Next, put the new dop into the clothespin, immerse the dop into the clean alcohol, and wipe clean with the tissue. Now place the cool dop and gem into the dopping jigs heat-sink side.
16. Heat the new dop as we did earlier, and get the cone dop (if that is what you are using) filled to the top with wax. It is ready to insert into the transfer jig, but wait!
17. Now heat the transfer jigs metal in the alcohol lamp flame so that it is definitely hot. Turn the metal so that heat is warming it from both sides. You want it to stay hot. You can make a fast test, by licking your thumb and index finger and then pinching the metal quickly; to be sure it is hot.
18. At this point, I re-heat the new dop (which is still pretty hot from before), to make sure it is full of hot wax. Then I quickly set the hot dop into the transfer jig, and using the clothespin, I push the hot dop and wax onto the pavilion of the cold side of the jig. Press the cone dop onto the gem just that once, and quit. If you push again, you will probably find that heat has already been transferring to the cold side, and you may move the gem. When the wax is still very warm, I do the wet finger pinching around the new dops attachment point to the gem, to help the bonding area. Do not use a wet rag. Let the jig set unmoved, until it cools in the air.
19. When I take the resulting two dops holding onto one gem out of the jig, I am very careful so that the joints are not jolted by hitting anything. We want to be sure it is a good bond. I do not want to find it is a poor bond when I am later cutting the Crown. So, I hold onto both dops, and pull directly away from the gem from each side. Use a reasonable amount of pulling force, not heavy. I even move the two dops in my fingers, and try to pull them apart for a second time. Be sure that no bending of the dops is tried. That would snap off almost any good bonding. We just want to be sure that the bonding will not break with just a light force being applied.
20. Now attach the clothespin to the crown-table side dop, the dop that you want to remove. Heat that dop in the alcohol flame just enough to be able to pull the two dops apart. Again, pull apart. Do not bend the dop out of the wax.
21. I heat a pocketknife over the flame until it will scrape the surplus wax out of the way. This has to be done very carefully, if at all. The metal of the knife could damage the previously faceted pavilion facets and the girdle facets. So, use common sense, especially if this is a competition stone that you are working on.
22. Soak the old wax off of the old dop, in a small jar of alcohol labeled “dirty alcohol”.
23. There is no real need to risk damage to the gem by using a hot metal knife to clean away surplus wax. The only reason may be to show where crown facets need to meet girdle facets. The surplus wax will easily grind away once cutting of the crown facets begins.