Jade polishing

Hi,
I am trying to reconstruct the polishing technique my grandfather used in the 1960s for jade. He got excellent results and avoided orange peel. I have the original leather laps he used, which range from 3,000 to 100,000 grit. What I haven't been able to determine is what polishing material he used...I assume diamond or carbundum. The laps have a reddish stain on them similar to rouge.

Anyone know how can ascertain this?

FYI, as a child I sat at his side and watched him work, and am now setting up his old equipment...the challenge is figuring out exactly how he did it.

Thanks, Doug

Good luck, Jade is tough to polish period.
Tell us if you figure out any tricks.
This took me about four hours to polish.
AK

Carborundum and aluminum oxide only get to 3-4,000 grit. The sizes sound like diamond powder/paste.

Hi
I have had some jade that polished easy with no orange peeling and others that I couldn't get a decent polish no matter what I did. One old lapidarist that I knew told me to use a worn out 600 grit belt dry. I have tried this and got good results most of the time. The stone will get quite hot and you have to be careful the stone does not pop off. I have had better luck using the resin bonded diamond sanding disc with water on a hard flat wheel. They are maybe 1/16 thick or less and have less give than the belts on a expanding drum. Diamond is also better because it maintains its cutting edge longer and doesn't round off. The disc are made by several companies such Ameritool and Crystalite. Diamond is more expensive of course but last a long time and more than worth it in time saved and overall cost. They come in grit from 220-8000. When it comes to polishing a lot of people use Chrome oxide on leather but I have never tried it and generally just use Aluminum oxide then diamond paste if you want a higher shine. Jade is one of those stones that usually does what it wants no matter what you do. I hope this helps some.
Donald

Jade west , a Canadian company that mines, processes and sells jade and jade items world wide, uses diamond from first to last, as far as I know.

As a side note...folks with more time spent on this than I suggest that the first step to nephrite jade work is to cut the raw material in three different directions.Then do a polish on the three sides, one direction will be better. The claim is that nephrite morphs the actinolite/asbestos crystal which are more or less laying flat next to each other. So if they are right then one direction you will likely go across or perpendicular to the crystal which does not polish well. In my playing with this it appears to be true. Also since nephrite is a metamorphic material there are always inconsistant results thats why the stuff looks different from different locations. Not unlike a cake mixed and baked at a different temp.

I tend to have best results with diamond. Kind of sounds like your grandfather may have used a red rouge bar to help keep the diamond charge on the lap.

Doug,

Jade is not that hard to polish with the right tools. and good jade. Not all jade will polish well.

I have made jade cabs, spheres, book ends, and just polished pieces for decades with and without orange peel. I use a Genie starters. When I get to the 600 grit stage, I switch to a wornout 600 grit silicon carbide belt. After that I use a leather or felt buffing wheel at slow speeds with tin oxide and a very light touch. You can get really good results with 3,000 grit diamond paste inplace of the tin oxide.

This is just one method. I am sure there are others.

Good Luck,
Rick

I just wanted to point out that Chrome Oxide is very, very messy! I've found it works OK on Jade, and serpentine as well, however, its hard to get off your hands and out of your clothes, and I'm not really sure why anybody would want to use it on a non-green jade. I've found alot of reddish rust colored minerals on the skin of river worn Jade and it makes a huge mess when cutting if its a soft rind. Wonder if that could be a source of the red in the leather?

Thanks,

Aaron

Re: Michael Croxell comment on jade structure.
The toughness of nephrite jade is due to the "micro-interfelted" texture of the tremolite/actinolite crystals. There is no directionality to this texture. Sometimes, there are veins of parallel growth tremolite within a piece of nephrite which exhibit chatoyancy, but these are probably not tecnically nephrite themselves. There is a lot of variation in a jade deposit and many associated alteration minerals and inclusions. Talc, asbestos, serpentine, coarser tremolite/actinolite are common associations with the metasomatic process that forms nephrite. Uvarovite and chromite are common inclusions. The relative hardness and size of inclusions can influence the quality of the polish. The grade of the nephrite is related to colour shade and the brightness of the polish it takes. Nephrite is also subject to retrograde metamorphism,where it starts to become serpentinized. High pressures also cause some to be schistose or irregularly micro-fractured. These changes all affect grade, toughness and polishability. The value per pound can vary from a few dollars to around a hundred dollars, depending on quantity purchased. I guess this old jade miner/geologist just got triggered into rambling a bit.

Alex,
Ramble on! What areas have you mined jade? Have you ever collected in Washington state? I appreciate your prespective on jade, especially in regards to it's variability. I'm still learning the ropes, but I think I'm past the neophyte stage:-) Have you any interesting examples of jade? Blacks, patterned, botryoidals, reds?
It was my understanding that the "orange peel" is caused by the "undercutting" of softer inclusions. It is also my understanding that the difficulty of cutting/polishing jade has been over stated. Traditionally beeswax has been used as a final treatment to jades...perhaps to combat a little left over 'orange peel'?

~Zeke,
JadeJunkee
Washington State