The Art of Dopping – Martin Winterbottom
Dopping is the art of securing stones to a stick so that they can be cut and polished. This is rather like other lapidary techniques in that once several methods have been tried and the best found there is a tendency to rely on that method and concentrate on other aspects of the job in hand.
A CONVERSATION with a jeweller friend having problems getting stones to stick with wax made me rcalise that I too have been through failures and frustrations with stones flying off at awkward moments (some never to be found!) and the idea for this article began to materialise.
I describe dopping as an art because of the need to get the right amount of 'stick' - not too little so that stones fly off, but not so great that the removal of the stone itself causes damage.
I have met people who avoid dopping at all costs, being able to hold and manipulate small stones against wheels and discs. These people are rare and I am not one of them.
The time honoured method of securing stones to dop sticks is by means of dop wax. It comes in a range of formulations with different melting points, 'stickiness' and 'gooiness' when warmed up. Again trial and error is a good thing to find which type suits you best. There are some golden rules for using dop wax without which it will just not work.
The stone must be clean and free from dust and any oily residue. Oils from sawing are best removed with methylated spirits. The stone must be at the same temperature as the molten wax for it to stick. A little warmer is fine, but cooler will not work. Obviously fragile stones will need care and indirect heat is best.
Polishing can generate a lot of heat which may melt the wax before the work is complete.
There is no easy solution to this other than keeping wheels and discs well lubricated and taking time to let heat dissipate. To remove the stone either warm it and
scrape off surplus wax or place the whole thing in the freezer for a few minutes to allow the stone to be easily parted.
My favourite method, both for cabs and faceted stones, is to use epoxy resin to glue the stone to the dop stick. I prefer resins which harden fairly quickly but remain slightly rubbery which can be peeled from the finished stone. A disadvantage is that stones cannot be cut immediately; sufficient time must be allowed for the glue to gain strength. The main advantage is that no heat is involved and even the most fragile stones can be held. Cleanliness is again important to get a good bond.
Removal of stones held by epoxy glues needs a little care. Metal dops are easy as the dop can be warmed slightly and the stone peeled free as the glue softens before the stone becomes too warm. Wooden dops can be sawn off if troublesome and any really old or very solid epoxy ground from the back of a cab on a flat
lap. I try to avoid solvents as only fairly nasty ones like paint stripper will soften hardened resins. A technique which is useful for durable stones is to deliberately build up heat at the very final polish so that the resin softens and again can be peeled from the stone and the dop.
I have been advised that some people get very good results from superglue, again using heating techniques to remove finished stones, but I have only really tried this when a stone has come away from the resin on a dop and needs to go back in exactly the same spot. Results are almost instant with this method and smooth,
square-ended dop sticks are essential as a close fit is needed for a good bond.
Also sold are systems using a sticky double-sided tape to hold stones on to smooth metal discs with a threaded handle. I have not yet tried these, but I suspect cleanliness in mounting and care in removal are similarly needed.
If you have managed to get this far, well done. I think only fairly keen lapidaries or those keen to have a go could find several hundred words on the subject of sticking bits of stone to bits of stick fascinating. Those like me who never cease to be delighted by a well finished stone might like to go back and try something
new or something again. Happy dopping! RG
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