23 Jun Dopping Opal
What on earth does “dopping opal” mean?
If you have ever tried cutting and polishing opal or any other small stone by holding it in your fingers you will know it is very difficult to do and will often result in grinding a hole in your finger as well as ruining the stone.
The solution is to glue the opal onto the end of a small stick or nail. You will then have much better control of the cutting process and it is much safer.
Some people glue the stone on using araldite or a similar two part epoxy resin but you need to allow this to set for many hours before cutting.
I prefer to use dopping wax which can be purchased quite cheaply from a lapidary supply store or from an on-line store.
The reasons some people do not like to use dopping wax are:
(a) You have to heat the opal to get the wax to stick.
(b) The wax does not always stick to the opal and the opal can fly off during the cutting process.
(c) You can burn your fingers while moulding the wax.
Unfortunately all of these reasons are valid but with a little care wax-dopping can be quite successful 90% of the time and cutting can be carried out within minutes of fixing the stone to the dop stick.
To ensure you do not damage your opal if it does come off the dop-stick place an old piece of carpet or a rug around your work bench so the opal will not land on anything hard.
For dop-sticks I use 150 mm lengths of 7mm dia wooden dowel for larger stones and similar lengths of kebeb skewers for the smaller ones. Make sure you cut off the points of the skewers before using them as they are very sharp. Some people use nails but I prefer the feel of the wood.
Before dopping it is wise to grind off any sand, clay or loose material from the face of the stone to which you want to attach the dop-stick. This will ensure a better grip.
The first stage is to melt a blob of wax onto one end of the dop-stick. Heat the wax just above the flame of your spirit burner until it becomes soft and pliable. Don’t put the wax directly into the flame because it will catch fire and become black and very messy. Once the wax is pliable rub the end of the dop-stick onto the wax stick and the wax will transfer easily to the dop-stick. While it is still pliable use your fingers to mould the wax around the stick so there is approximately a 1 mm thickness around the top 10 mm of the stick and then form a point with the wax.
A good tip is to wet your fingers before doing the moulding so the wax does not stick to your fingers and burn you. Also make sure the wax is just pliable and not melting at this stage.
Next you need to warm the opal. Be very careful not to make it too hot or it could easily shatter. I find holding the opal in my fingers while passing one end just above the flame usually works if the stone is large enough. You can use tweezers for smaller stones but be careful as they heat up very quickly. Again do not put the opal in the flame but move it about just above the flame. Putting it in the flame will put a black sooty coating on the opal and this could stop the wax sticking to the stone.
Having warmed the opal, now heat the pointed end of the wax until it is nearly melting and then smear a bit of the wax across the face of the stone you wish to stick onto the dop stick. If the wax adheres to the stone then quickly push the still warm waxed end of the stick onto the stone with the melted wax. This should give a firm bond. Now knead the wax against the stone making sure the dop-stick is as close to the centre of the stone as possible and with the stone at right angles to te dop-stick.
Let the wax cool for a few minutes. Don’t dip it in water to cool it faster as it will probably lose its grip and come off the stone.
If all has gone well your stone is now ready for cutting.
Photos will be added late.