Below I will explain how I dop with two part epoxy. My methods and technics are somewhat different from the ways of many other faceters. I will also try to provided the reasoning as to why I dop stones the way I do. Hopefully, this information will help others who are faceting stones.
Initial Dopping of Rough Faceting Material
- Determine which side of the piece of rough will be the table of the stone. Grind a flat (260 to 600 grit) on the table side of the rough forming a temporary table. You may have done some preforming to the gemstone rough prior to this step .
- Set up the transfer fixture for dopping the gemstone rough. Insert a 1″ or larger dop or flat target dop into one side of the transfer fixture.
- Place a small bit of putty on the large flat dop. I use Play-Doh. Play-Doh is inexpensive. It is generally a one time use item. I gets hard after being out for several hours.
- Determine what the approximate diameter or narrowest width of the finished stone will be. Select a dop that is approximately 1/4 of that diameter. The smaller size dop is used because you DO NOT put epoxy on the flat end of the dop. Also, using a smaller dop allows you to create a larger filet of epoxy around the dop.
- Clean the dop you selected and the temporary table of the rough with alcohol.
- Select an additional flat dop that is the diameter of the stone rough or is as wide as the narrowest part of the stone rough. This dop will be only used to help center the stone rough, in the putty (Play-Doh) and make sure the temporary table is flat against the dop (perpendicular to the axis of the transfer fixture).
- Place the stone rough into the putty (Play-Doh) with the temporary grind table facing up.
- Using the temporary dopin the transfer fixture to center the stone rough and then press down on the temporary table to set the stone rough in the correct position for dopping. Be sure to press the stone rough down so it hits the target dop below. You can push the putty (Play-Doh) up around the stone rough to tighten the stone rough in place.
- Now remove the temporary dop you used in the transfer fixture.
- Now insert the clean dop, you selected earlier, into the transfer fixture.
- Press the dop down until the flat end touches the temporary table of the stone rough. Sometimes I add a very small amount of epoxy around the circumference of the dop prior to placing the dop into the transfer fixture.
- DO NOT put epoxy on the end of the dop. You will see why this is so important when we get to the removal of the dop.
- Add epoxy around the shaft of the dop and the stone rough to form a nice tapered filet of 5 minute epoxy. (See epoxy mixing instructions).
- After the epoxy is applied you hold the transfer fixture so you can flip it up and down. You need to do this so the epoxy doesn’t flow all in one direction.
- By flipping the transfer fixture up and down you form a nice filet of epoxy between the stone rough snd the shaft of the dop. The putty (Play-Doh) helps keep the stone rough in place.
- You need to keep flipping the transfer fixture up and down until the epoxy starts to set. Once the epoxy is setting up, you then set the transfer fixture aside.
- I usually wait over night for the 5 minute epoxy to fully cure. I usually have several stones that I’m working on, so waiting over night is no big deal.
- The stone should now be securely attached to the dop in the proper orientation for cutting.
- Happy cutting/polishing of the stones pavilion.
Notes on Mixing 5 Minute Epoxy
- I use either Harbor Freight 5 minute epoxy or Vigor 5 minute epoxy.
- I like these two brands because they come in small tubes. You do not have to worry about the epoxy getting old. It is also easier to mix a very small amount to dop a piece of stone rough.
- I mix on a small square of cardboard type paper. The cardboard squares are approximately 2″ x 2″ or so.
- 3″ x 5″ or 4″ x 6″ note cards could be used. Any cardboard material similar to this could be used. I usually find things that would go into recycle that I can cut up. A piece of paper would work but the epoxy can soak through. Some people use a 3M Post-It pad to mix on.
- For a small stone I only use a size of a chocolate chip size of the epoxy.
- I mix the 5 minute epoxy using a tooth pick. I prefer flat tooth picks. That’s just me.
- I mix the epoxy for 30 seconds to one minute .
- I use a second clean tooth pick to apply the epoxy to the dop and stone rough. Using a new tooth pick I have better control of the amount of the epoxy that I’m applying.
- Using a clean tooth pick also removes the chance of getting any un-mixed epoxy on the dop and stone.
- SPECIAL NOTE: Your dops should be very clean. Free of any residual wax, super glue or epoxy.
Epoxy Mixing Supplies
- 5 minute epoxy
- Mixing pads (cardboard, paper, etc.)
- Tooth picks
Pre-Transfer Dopping Notes
- This method of using epoxy to dop stones will allow you an easy way of transferring the faceted stone using epoxy dopping on both sides of the gem stone. No heating of the dop stick is used in this method to remove the original stone.
Transfer Dopping with 5 Minute Epoxy
- Pick a cone dop for the transfer which is one half or less of the diameter of the stone or minimum width.
- clean the stone and dop with 91% alcohol.
- A smaller size dop allows for a larger filet of epoxy.
- Place the dop withe the stone into the transfer fixture.
- See notes on mixing 5 minute epoxy.
- Place a small amount of epoxy on the outer edge of the cone dop. only a small amount of epoxy is needed long the inner taper of the cone dop.
- DO NOT fill the dop with epoxy.
- Place the cone dop in the transfer fixture.
- Press the dop up to the stone.
- Adjust the indexing if your dops are indexed.
- Add epoxy around the stone and dop to create a filet between the stone and dop.
- After the epoxy is applied all the way around, you hold the transfer fixture so you can flip it up and down. You need to do this so the epoxy doesn’t flow all in one direction.
- By flipping the fixture up and down you help form a nice filet between the stone and dop.
- The small amount of epoxy in the outer edges of the dops cone add strength in holding the stone.
- By not using large amounts of epoxy inside the cone dop, the culet is protected.
- See notes on modified cone dops.
- Leave the epoxy cure overnight.
Stone Transfer – Removing the Original Flat Dop
- Keep dops in original transfer fixture.
- Heat up the Xacto knife blade with an alcohol lamp.
- Using the hot Xacto knife start cutting away the epoxy on the side with the original flat dop.
- You will only be able to make a couple of cuts before you need to reheat the Xacto knife blade.
- Reheat the knife blade often.
- Cut away all the epoxy around the flat dop.
- Cut epoxy down to the metal dop.
- Cut epoxy away up to the flat temporary table of the stone.
- Once the epoxy is removed all the way around, remove the stone with the two dops.
- Place the stone with the two dops on a wash cloth or small towel.
- Tap on the dop where you cut away the epoxy. The dop will pop off as there is no epoxy on the end of the dop.
- The dop may separate before you get the whole thing out of the transfer fixture.
- Once the original dop is remove, you may need to do a little cleaning of the temporary table surface with the hot knife prior faceting the crown.
Suggested Stone Transfer Supplies
- Previously dopped stone with finished pavilion
- Transfer fixture
- 5 minuted epoxy
- mixing pads
- tooth picks or equivalent.
- Alcohol lamp
- Matches or lighter
- Xacto knife with something like a #11 blade.
- Alcohol 91%
Additional References
Article named “All Epoxy Cold Dopping Method” by Chuck Gartmann in the United States Facters Guild Newsletter, volume 32, Number 3, September 2022
On YouTube a video entitled “How to Cut Gemstones/Opal Faceting in 4K” by Steve Moriarty. Steve shows this epoxy dopping method.