Sealing natural stone for a pendant

Hello,

I obtained some stones that although beautiful, are soft and have a
high amount of grit so I’ve been advised against polishing them. When
I said I wanted to make pendants from them (probably with wire
wrapping), the proprietor where I got the stones from recommended
coating them with polyurethane so the stones wouldn’t wear down as
someone wore them.

My questions to you are:

  1. Is there a specific type of polyurethane you would recommend for
    this?

  2. Is there a specific number of coats I should apply?

  3. Is there a specific method of application I should use? If yes,
    please describe it.

Thank you so much for your time.
Elaine

I obtained some stones that although beautiful, are soft and have
a high amount of grit so I've been advised against polishing them. 

This is hard to answer without knowing what they are, just how soft,
or what “a high amount of grit” means. But on the basis of what you
said, I would say, any kind of coating will tend to make them look
like patent leather. If these pendants are for your own use, then do
anything you like and see where it leads you. If they are supposed to
be to sell, then either your wire-wrap should be designed so that
nothing can knock or rub the stones, or, better yet, put them
somewhere (on a shelf) that you can enjoy their beauty, and forget
about setting them. Our customers have a right to expect a certain
level of durability in what we sell, plus clear disclosure/education
on stones that are fragile but too gorgeous to pass up, such as opals
or tanzanites.

Noel

The stone in question is known as Kanab Wonderstone (rhyolite,
sandstone, and iron oxides), and its complementary stone know as
Goldenstone. The grit I spoke about comes from the sandstone. They
are truly beautiful pieces that I want to be able to sell as pendants
(just pendants, no other kind of jewelry will work with it). I
absolutely agree with the sentiment of "Our customers have a right to
expect a certain level of durability in what we sell, plus clear
disclosure/education on stones that are fragile but too gorgeous to
pass up, such as opals or tanzanites.

The problem is what to seal it with. Should it be polyurethane? What
kind? If not, would a resin be better?

Thanks.
Elaine

The stone in question is known as Kanab Wonderstone 

Isn’t wonderstone the stuff that was the subject of great
controversy, a number of years ago, about whether it was really
natural stone or man-made? Was that ever settled?

Elaine,

Even though the stone won’t take a polish, it can still be smoothed
so the surface isn’t as gritty. I’m still not understanding what
you’re trying to accomplish by sealing the stone though. Do you want
a shiny surface? Do you want to reinforce the stone so it’s less
fragile?

A shiny surface would look very out of place on a sandstone. Because
of the fragility, a protected setting would be far better, IMHO, than
putting a sealer on the stone.

Cheree

Elaine, When needed, I typically use Hxtal, as a stabilizer. It is a
high quality, professional grade, glass epoxy. When mixed and
applied, per manufacturers instruction, it takes a week to penetrate
and harden. Virtually invisible and extremely hard.

Dave Leininger

Isn't wonderstone the stuff that was the subject of great
controversy 

This particular variety seems to be legit. Here’s an abstract of a
technical presentation about it:

http://www.ganoksin.com/gnkurl/ep7zpy

Al Balmer
Pine City, NY

The problem with wonderstone is that because of the high sandstone
content, it’s gritty throughout. I’d like to smooth it a bit, but
the real reasons for me wanting to seal it is so a) the grit won’t
get on the wearer’s skin, and b) the stone won’t wear down as it’s
handled. A protected setting is crucial, but if it’s wrapped too much
then the beauty of the stone would be lost.

In response to whether wonderstone is real (i.e., not man-made yes
indeed it is. I’ve seen it myself in it’s natural state…gorgeous!
I don’t know anything about a controversy, but it is indeed real. Do
a search on “kanab wonderstone” and look at the images for it.
Amazing! What I have is actually “golden stone”, which has a darker
coloration but is beautiful just the same.

Elaine

I’m very familiar with Kanab and especially wonderstone. I use to
know the man who had the claim to the most poplar mining site. It’s
sandstone. The Rhyolite version is a harder version that comes more
from the St. George area, and the Force family had that mining claim.
It was known as Utah picture stone. Wonderstone will stand up better
than turquoise. Many here will have formulas they use to stabilize
stones. A lot are forms of epoxy that has been thinned down. In the
Southwest they don’t seal jewelry made with the wonderstone. Just
putting a coating over the top of wonderstonw ill in time peel off.
The grit you refer to is what will not let it adhere for long.

Goldstone is glass that has had copper filings added to it to make a
stone of sorts. You can get in in green blue and the most used red
versions. It was first made in the Gallup NM area.

Aggie the old lady in Florida who voted sand now has 4 more years of
bit**ing rights

Isn't wonderstone the stuff that was the subject of great
controversy, a number of years ago, about whether it was really
natural stone or man-made? Was that ever settled? 

That is Rainbow Calsilica I believe. I heard a report that said
someone tested it, and one of the ingredients was paint. Also the
mine owner wouldn’t let anyone in to see the origins of the material.
But it’s an interesting looking stone, anyway.

Vicki K, SoCal

Goldstone is glass that has had copper filings added to it to make
a stone of sorts. You can get in in green blue and the most used
red versions. It was first made in the Gallup NM area. 

Actually goldstone dates back to the 17th century in Italy. The
commonly accepted story is that some monks were making stained glass
and were adding copper salts to molten glass for coloring and added
too much and the copper solidified creating the copper sparkles in
the glass. Some people dress up the story a bit as monks working with
alchemy. The best documented inventor was Vincenzo Miotti a Venetian
glass maker invented goldstone and the formula was a family secret
passed down generations. Some French scientists were able to
duplicate the results and around the end of the 19th century
goldstone made an appearance in the US.

There is a good article on mindat.org detailing the history of
goldstone.

Rick Copeland
Colorado

I’ve heard it was a byproduct of Mexican ceramic manufacturing. They
let the waste ponds dry up then mine it and stabilize it. A friend
who is a rockdealer has a picture of a bottle cap in the middle of a
piece of rainbow calsilica which I take as proof it’s not anything
nature created…

Rick Copeland
Rocky Mountain Wonders