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jade undercutting


Shane

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  • 2 weeks later...

Hi Shane

 

What do you mean by under cutting? Is this BC jade and as you are sanding you see an orange peel like surface?

 

I have found some of the BC jade that is less translucent with black markings orange peels very quickly. From my readings this is caused by softer areas in the stone pulling off the harder stone. Sanding with a soft backing to the sandpaper appears to be worse. I have recently finished a small piece that I sanded more successfully. I used a homemade bur. I took a piece of pear wood and shaped a small bur and mounted the wood to a threaded mandrel. I charged the wood with 600 grit diamond paste. I made a second one and charged this one with 3000 grid diamond paste. The sanding was better then my attempts at sanding by hand. I next used a felt bob with platinum rouge to finish the polish. I think you can read a few of the other threads on sanding and polishing Jade for other ideas too.

 

Russ

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  • 2 weeks later...

hi shane, Iam still learning how to carve jade.

At the course in newzealand ( cert 4 carving Jade and hard stone) I had the constant bugbear of what you call undercutting while sanding my jade carving.

 

Russ I agree with you totally.Wee called it orangepeeling to.

with small carving it is hard to detect it while doing the shaping phase.

it turns up as a problem once the sanding process begins, usually arfter the 600 gsm sandpaper is used.

 

As Russ said, the softer parts will start pulling off the harder stone. If the carving was really big you could run your finger along the affected area and feel low pits ,then high pits( thus it looks like an orange peel ).

the idea is to think like this when sanding , and if it does happen then you need to use 600gsm sandpaper or even lower( we had access to the much loved expensive diamond paper) and sand your carving /or area affected ,

again to create a new surface that is all the sameheight.

 

. this will take off some of your hard carved area, so go slow, use long strokes apon yourcarving ( even go so far as to draw lead pencil marks where it should be sanded away -that way you definately have sanded that area )

trail out sanding across then along the troublesome grains Shane, as sometimes that worked when I was totally ready to throw away my carving in frustration, it will sand the higher harder stone down to the same level as the softer pulled out area.

then it should be back to you sanding up to say 2000gsm and onto polishing.

 

when sanding we were told to also use the largest sanding drum as possible to maximize a bigger surface area sanded at once, and that way the pressure on the softer bits is minimalised this way.

 

with my carvings of jade , if they were undercutting while sanding then Iswitched to sanding with water only and applyed less pressure.

The jades with fibres present are a real ummmmmm pain to carve, as they pull out easily, and the bc jades with black spots were also prone to orange peeling.

 

Good luck with your carving Shane, remember the shaping of the carving is only half the process, as the sanding ,and then polishing is the other slow laboriuos half.

That said if their is orange peeling ( or many scratcies) the shaping will be 1/3 and the rest will be frustrating sorting out sanding problems ,

and then the extra reward of a finished polished carving.

 

Have a good day we are trying to deal with a heatwave here in australia , so no carving for me today.

 

naomi.

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Shane:

 

Ditto to what was said above, but you can also try brass rod in a rotary tool with varying grades of diamond powder with oil.

 

The amazing and incredible Donn Salt (see the members list and click on his website) uses a variety of stones in various grades, I believe. I haven't tried it yet, but his work is some of the finest I've ever seen. I'm buying stones after my next big sell.

 

Lapidary people, when making cabochons and the like, use a "spool polisher". This is a polisher whose wheels are made or macardia or maple, and then charged with diamond powder. The point of all these methods is that the polishing element is hard. The softer the wheel is the more likely the stone is to undercut.

 

If you think jade is bad to polish, try llanite. It's next to impossible to get a finish on, being comprised of crumbley limestone and really hard quartz.

 

Good luck!

 

Debbie K

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  • 1 month later...

Yes russ it is the b.c jade with the black spots..i was really surprised at how fast it orange peeled.. iv read a little more about polishing jades that undercut. and lots of people recomend the method u said about

the burs with diamond paste it sounds like it works pretty good. but when u say charging the burs with diamond paste im a little unclear on what that means??

 

and ya naomi iv definetly realized that carving is only half the part of making a carving

It's too bad that with stones that undercut the shaping phase is the smallest part cuz thats definetly the funnest by far!!

 

it;s really great to see soo much advice towards this topic:) it's muchmuch appreaciated to you all!!

and donn salts work just leaves me in awww.. it crazyy!

 

Shane

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dear shane,

 

glad to have been able to assist .

 

At present I am carving South australian jade into pendants. I am still on the shaping stage, using my new lapidary grinding machine.

Thankfully it is a strong compact stone, that is not undercutting at all.

next week I am purchasing tin oxide powder from an australian lapidary supplier.

 

Over here I am having trouble locating a supplier of diamond abrasives, who sell rolls of diamond paper, that are around 60mm across and can be cut into about 210 mm long strips.

( these are attached with an elastic band onto a attachable drum point

. this point is placed into a chuck that is a part of the grinding unit.

the drums come in various width sizes and are great for sanding and polishing smaller carvings)

 

when orange peeling occurs the diamond paper will even the top layer down to the undercut area quickly.

 

keep enjoying carving jade, shane, I too love Donn Salts work, he is one of my inspirational carving artists.

We too will become experinced jade carvers the more we do.

 

this picture is the grinding machine, and point carver setup we used in the jade carving course in new zealand. the machine alone costs 3k so I make do for now. it does give everybody out ther an idea of what the professional jade carver in new zealand could be using today.

 

post-2-1266377436.jpg

 

 

happy carving everyone

 

bye for now Naomi.

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  • 6 months later...

Shane,

I to had my hard times with producing the best of the best shine on more than a few stone types in my career. In 1981 I found a stone that was almost impossible to get the killer shine on Sugilite. If you go to this link http://www.lopacki.com/tips/ and see what I have to say about water wet polishing I assure you that it will be of help to your problem.

 

When I can’t use a wooden wheel I’ll use standard dowel rod in various diameters, stick a piece in the Foredom hand piece shape it with a file then use it with diamond powder and oil, I have even been crazy enough to use toothpicks in this way when doing the final finish on Fire Agate.

 

Check out the link, if you have further questions feel free to email me.

 

All my best ...... Danny

 

P.S. The wooden wheel eliminates all orange peel.

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  • 5 months later...

Hi Daniel, and everyone else here!

 

I was REALLY considering NOT posting a question pertaining to how to pre-polish a piece of jade before the final polish, mostly because SO many people have asked the same thing, and received the same answer, which is READ WHAT IS WRITTEN HERE!! LOL

 

Well, I HAVE done that, but I must say that I'm still a "little" confused about what the BEST method is, and that is because there are MANY more than "one way to skin a cat" as you might put it, (my wife would smack me for using that saying, she LOVES her kitties, hehe) and also, some of the techniques to do so are not really for tiny little detailed types of carvings, but rather larger flat surface type of carvings, which at this time, are not really what I've been working on.

 

I have read Daniel's suggestions of using the wooden mandrels charged with certain diamond powders and oil, and also some others that suggest a brass one to do the same thing, which are techniques for pre-polishing very detailed carvings to ensure that the little nooks and crannies don't get missed.

 

Daniel's suggestion is the exact technique I've used for opal polishing when doing a carving, as well as putting a piece of wet/dry sandpaper on a split shaft mandrel to also sand down some of the larger places on the carving, which also works well, but is a pain to do!

 

One problem I always have when doing a pre-polish with oil based diamond pastes, or with mixing diamond powders with olive oil, or baby oil (mineral oil) is that suddenly all the flaws disappear, and it is SO hard to see where it needs to be polished, so I end up scrubbing it with alcohol to remove all the oils so that I can view it under the loupe and actually SEE the tool marks and scratches, which is why I many times get frustrated, and end up polishing with water ONLY and with fine wet/dry sandpapers, as then, I can SEE the scratches, but with that technique, I just can't get into those hard to reach places.

 

Recently, I've purchased some soft silicone rubber polishing bits that are impregnated with different grits of diamond powder, but find that they just are NOT working as expected on the jade, especially the BLACK Guatemalan jade, as it is SO hard. So I think that THAT method is a no-go for now.

 

What concerns me about this stage of the polishing is something I've encountered MANY times with polishing an opal carving, and that is that the actual original detail of your carving may change without you really being aware that it is happening, until all of a sudden, you realize something is different, and that is also WHY I take pictures of my carvings at various stages of the carving process, so I can SEE with my own eyes the differences, and don't have to rely on my memory. When you do this, you can REALLY SEE the differences that can be made in the pre-polish, such as things "shrinking" substantially, or the original shape of your carving subtly changing ever so slightly.

 

I guess it's not really a problem, as long as it still looks good, but I think that it's a good idea to not have something "drift" into something else without one being aware of it! Has anyone else ever had this experience?

 

So I guess my question is, what is the least invasive pre-polish that will keep the detail (tumbling is out for that reason!) in a carving, and not change the original shape of it too much, while still getting rid of all the tool marks ect, and getting it ready for the final polish?

 

I know the answer to that is going to change depending on WHO answers it, but that's OK, I like to hear everyone's techniques so I can try them all myself.

 

Another dilemma I am having, is whether to even POLISH some carvings or not, as in the past, I've carved things that just didn't look "primitive" or primal, as they were intended to appear in the end, so I guess there are some cases where to don't really even want to polish something to a high shine, such as when your trying to carve a replica of an ancient Mayan type of artwork, as they just didn't polish things to 50,000 grit!

 

I guess that's just something you learn to "envision" with experience, as in the past, I have had the end result being disappointing (only to ME though, because it just didn't match what was in my head!) because in my opinion, the carving ended up looking more like a piece of "plastic", and "too perfect" for the primitive look I was trying to achieve.

 

It's hard to switch from producing opal cabs where you're concentrating on the most absolute perfect and highest shine possible for opals meant to be mounted in a consumer's piece of jewelry, where you just "automatically think" that way, to having to actually "judge" whether or not a carving actually NEEDS a final polish, and if so, how much before it looks like plastic mass produced junk...lol.

 

I hope I'm making sense!

 

Again, I know that I'm asking the SAME question that has been asked a thousand or more times, but I just want to get it clear in my head what the best and easiest approach to polishing fine detail is, such as with what kind of polishing media (diamond, silicon carbide ect) and what is the best delivery method to apply that media to the carving "with", and to what degree of polish is an industry accepted standard polish that a customer would expect when purchasing a jade carving, because as you know, polishing an opal is DRASTICALLY different than polishing a piece of jade, and sometimes, the biggest mistake you can make if you are producing a carving that will eventually be for sale, is to NOT do what a customer would want, and DO what YOU would want for "yourself"!

 

Thanks all for your patience with me!

 

Chris :D

 

 

Below is my first ever Guatemala black jade carving, it's at the stage where it needs the pre-polish, and then of course the "appropriate" polish. I don't like posting pics of things that aren't finished yet, but this just gives you an idea of where I'm at so far. It's all a learning experience!

 

Given the current "condition" I have with my hand control issues, that Foredom I purchased is making a HUGE difference in my ability to carve properly, and I've already learned ALOT just since purchasing that, so I don't regret it one bit!

 

Sorry for the crappy pic, my camera decided today was it's funeral day, and I'm attempting to use my wife's camera, which I'm unfamiliar with...lol.

Guatemala-black-jade-carving-10feb2011.jpg

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Chris,

I think you are right in the statement that some things do not need to be polished to a super high shine. As your carving stands right now it is quite imperssive with the satin finish, you might consider finishing it off at 600 and see what you think, I think it might just be perfect finished at 1200. The satin finish allows the viewer to see the depth and detail much easier than if it were finished to 14,000 or 50,000.

 

Just some feedback ......... All my best ........ Danny

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Chris:

 

From what I see from this piece, you don't need much advice. It looks really good to me, speaking as someone who is currently working on a jade (California Nephrite) Celtic Dragon. I think I have the marks evened out and then look again and see "cellulite". I've been using the stones (with water) that Donn Salt recommended, but you can't get everywhere with them. I do like the way you get a undimpled surface with them, just don't like the time it takes. From the look of mine, I've got several more days of hand work to do, which is way I'm taking a break from it today.

 

Regarding the degree of finish, I really agree with Danny. Some things look better satin, some glossy. The Chinese carvers seem to go for the high gloss finish, but I doubt very much my subject matter would interest this type of consumer. Not being a lapidarist first, I'm less concerned about a perfect finish than I probably should be. I try to view the piece as a whole and see what it wants to be and proceed accordingly. I try not to be sloppy; whatever level of finish I stop at I make sure I have no visible scratches. But since I carve alot of faces, I've found that they lose definition when really shiny. They look much better at a matte finish.

 

I have found it sometimes useful to go up one level of polishing and then back down. For example, if I want a 600 grit finish, go on up to 1200 and then back to 600. At 1200 you see more imperfections and can hopefully correct them, and then when you go back to 600 it really is the final finish, one without any problems.

 

Again, it looks really good and I'm glad you're having fun with it.

 

Debbie K

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Hi Chris

 

The following comments are on the points that you made at the end of your post.

 

You're getting into areas that only the artist should answer. Which comes from the image in your brain for what you wanted to achieve. Or as I am finding the final path my piece took which is not always the original concept. I agree with both Danny and Debbie but only partially. A matte finish looks great on some pieces, your piece looks great as it is to me, but only you can tell if this is what you really wanted. Where I disagree is some mediums beg to be finished to the best viewing of the medium. The following is not any comment on your carving:To me black jadeite finished to a matte finish is not appropriate for the stone. Black jade had an extra gift in that it is opaque in some areas and partially translucent in others, because the stone is so rare I would like to see any piece in Black Jadeite finished to show off the stone. But in truth you are the artist and this should only be your decision. Your carving will be around for the next couple of millenniums because of your choice of medium.

 

This going to be fun to watch your progression as you become familiar with carving jadeite.

 

For my last jade carving I used Debbie's suggestion and purchased the sanding sticks from gesswein and found they helped remove many of the scratches from the burs. What I did differently is I blended the sanding sticks with Danny's techniques. I created a slurry with the sanding stick then used hardwood on a mandrel to sand until the slurry vanished. then I would repeat. I switched to softwood, diamond paste and olive oil at 1200 and then 3000, and 14,000. I did use brass for the detail areas in the carving. I would only work a small area and clean the piece with a toothbrush and treated water to see the progress. It worked for me, and worked much quicker then all previous attempts. The hardwood I used is a pearwood that was collected in the Washington DC area. In NS you should have access to lots of Rock Maple, applewood or hornbeam (ironwood), the softwood I used is Tupelo Gum from Southern US, small pieces leftover from my bird carving days.

 

 

I enjoy your posts. And I too learn much from the responses from the other members in the forum.

 

Thanks

 

Russ

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Thanks Danny and Debbie, your advice is very valuable and obviously has come to you by much experience of your own!

 

My challenge is to take what I know about polishing opals, and use as much of that knowledge as I can to polish jade, this requires me to sort out the facts about what techniques are valid, and invalid basically, as applied to jade, so it's very helpful to have you guys point out things that you KNOW work, so I can cross them off that jumbled up flow chart in my brain for lapidary techniques...lol.

 

It's funny how you described going up and down in polish Debbie, as that is EXACTLY what I just finished doing tonight, I have a couple of different pre-made diamond pastes made by Engis in the UK, I purchased them on ebay as someone just threw them in with some diamond bits I bought from them, and it was really hard to even determine the grit size in the paste, as they were only marked by a code numbering system that I had to look up that STILL didn't really tell me what they were, but they seem to work really well on jade. I think one is 1200, and the other 1800 grit maybe, dunno.

 

I smoothed out the whole surface of the carving with regular diamond paste made for lapidary from Covington, a 600 grit, and got lots of orange peel, even though I used a bamboo skewer for a mandrel, so I just went back over it all with a very fine diamond electroplated bit also made by Engis, and once it was all evened out again, I just took a piece of this material that looks like a green scrubbie dish pad type abrasive, (only brown, made by 3M and I think 600 grit or so) cut it in a small circle, and mounted it on a screw on mandrel, then dipped it in the Engis diamond paste, and went at it.

 

It did alot better this time than the wood skewer charged with 600 grit paste, but didn't quite get into all the crevices, so I've still got alot more work to do!

 

I'll post a pic when it looks worthy of posting, hehe.

 

thanks again for your advice!

 

Chris :D

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