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Techniques for CollectorsStabilising before trimming?

9th Jan 2014 01:44 UTCDavid Baldwin

I found this fine looking baryte crystal yesterday...

The problem is, at present, the matrix looks like this...

It's a chunk of a septarian nodule about 12" across at widest point, and is composed of 3 major segments of rock. The main crystal bridges 2 of them, and I fear any attempt at trimming could fracture the crystal without some form of stabilisation.

My thoughts are that I could inject the deep cracks with some kind of epoxy or polyester resin and fill them to a point 1 or 2cm below the crystals to bond the segments, then carry out the major trimming on a diamond saw to remove some weight. My question is, would it be ok to have bits of the resin present as an integral part of the matrix, or would it be better to try and remove all traces?

Any thoughts or advice would be appreciated, thanks in advance.

9th Jan 2014 01:51 UTCReiner Mielke Expert

The most unique thing about it is the septarian nodule if you trim that away you have destroyed most of it's value.

9th Jan 2014 02:56 UTCRock Currier Expert

That's a tough call. Its kind of neat just as it is, but its a big rock with a little crystal on it. I guess it depends if you want a nice small little baryte specimen at the expense of losing the classical look of the nodule. As it is you have a nice big clunky specimen. I personally would probably just leave it as it is and put it away in a box somewhere.

9th Jan 2014 04:18 UTCSteve Hardinger 🌟 Expert

I like it the way it is, untrimmed. It says something about man's insignificance in an infinite universe.

9th Jan 2014 08:46 UTCDavid Baldwin

Interesting views, I personally aren't that keen on the massive nodule look, but that's probably because I know what will happen. I'm not ruling it out as a centre piece for my collection, but I don't think lots of these together would be particularly aesthetic. Another problem with these is that as they age and dry out, the cracks can open up naturally, which in this case would destroy both crystals. There is already evidence of cracking to the right of the larger crystal which has partly healed as it continued to grow. It's a shame, but over the years, many beautiful crystals have been lost due to this phenomenon, many in situ as they weather, others when the nodules are broken apart. I know these nodules well, and apart from the obvious cracks, there will be several more which have completely filled in with calcite. I've marked these on the following picture to illustrate:-

The solid yellow lines are areas where cracking will most likely occur, the dotted yellow ones are filled cracks which are probably stable and the blue dotted lines outline what I envisage as the trimmed specimen. In this case, I think the trimmed specimen with inevitably have saw cuts to the rear and possibly some resin/filler in place, traditional trimming is out of the question. What I wanted to know is how you feel about these aspects of a specimen.

9th Jan 2014 14:30 UTCReiner Mielke Expert

Why not just slice off the back so you have a thick slab of the whole thing, that way you reduce the weight but do not lose the unique character of the entire piece. You could then display it on a stand or mount it on a wall like a painting.The outer part of the nodule will act like a frame to keep the whole thing together and you don't have to worry about it falling apart.

29th Jan 2014 19:43 UTCJohn Oostenryk

David- Sounds like you been playing with these plenty to know the tricks/traps of success/heartbreak... Been there too LoL!

You are absolutely correct to do pre prep for success! Reiner said exactly what I was thinking though too. If no cracking, go!

If cracking- glue!

Definitely specimens can be cool with context- problem is they do kill a bunch of space. Over time, you decide to trim some back. I am there myself.

Curious, please, What state are you extracting these from? My experience with S IA was they do mean things when you saw without preprep...

When I first started sawing outdoors... Lots of loud cries of Arghhh and WHYYYY! Hopefully no one heard the 4 letter ones over screeching grinder... Surely horrible... I'm sure my neighbors thought I was cutting my fingers off back then- hahaha...

I am writing the text below to you~ but in a "generalized' tone for later viewers too:)

Stabilization... Get some super thin cyano acrylate(CA)(super glue) from a hobby store.
The regular store bought is NOT thin enough.
Also get the tiny thin extension tips. If you don't- You get glue everywhere -specimen sux- waste a lot - glue yourself to bottle and specimen...

Spend the $10 and have beautiful experience!

Store bottle in fridge- extends life a long time! Don't worry about capping the thin tip. I do try to "clear it" by squeezing at end.

If it drys closed, just snip bits with a scissor till you find the open 'neck'. If ya get to bottom of extension, take it off- pitch -start with new one. They are awesome lil tools!

Ask any Mineral or fossil prep person! Did I say awesome?!

--Insert tip down into the existing split, apply small amounts of CA- which will wick into cracks. Do this with pc laying flat on Back- so gravity points the way for glue travel.

--Glue will come out back if crack also goes through. (don't glue to hand or table)

--Any excess at surface should be dabbed IMMEDIATELY with a kleenex (NOT paper towel or toilet paper- they do NOT wick the glue up like Kleenex or are too rigid to press into surface irregularities for complete pickup of residual. Leaving a shiny glue line is ick.

--Let set overnight for full drying- 12+ Hours (I prefer 24 to be confident!) Too short and the piece will pop apart and wet glue will cement dust or frags where you don't want them or part will fall away to break... I KNOW. Don't ask~:)

Then use saw as much as you want.

Judicial mech trimmer impacts.

Or even very careful small hammer/chisel combo work on securely braced piece. (whole nother long writeup for that...) Caution but VERY doable...

I have had excellent success following these rules for CA.

Epoxy is basically nasty stuff in my book. Leave that to high-end casting and dyeing pros... Just Nah- good for fossils though!

CA is cheap and reversible!

CA glue messups or if applied for preventive insurance(so something fragile doesn't pop off)-- Can be easily removed by immersing in room temp acetone for a couple hours(or less).

for example: Either in bowl in icecream bucket with sealed lid or in a dish in a gallon ziplock. Don't breathe that vapor.

Remove, blot dry and set outside/garage~ to dry without fumes inhalation.

(Wear gloves for that removal;) dried out cracking fingertips suck!)

Also- super thin CA can be applied from backside via hairline cracks too... You waste a bit making a slight puddle line over crack but it will go in. Wipe back excess.

Certainly- this technique takes a bit of tinkering to 'master' so practice on some scrap pieces first. It really is easy enough after some mucking about:) Do not just jump in with best piece first.

Rock On!

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