Juma – A Composite Ivory Alternative

Block of Juma
Thick block form – great for knife handles.

What is Juma?

Juma consists of a mixture of different mineral based materials in a resin component. Unlike casein juma can be thermoformed using boiling water (according to Atlas Billiard supply.  Haven’t tried it yet myself).

Where does it come from?

Sources include Atlas Billiard Supply (cuestik.com) and suppliers in Europe (cuestik.eu)

Juma-03
It cuts well, dusting a lot like corian, but doesn’t have a scent.

How well does it cut?

Juma is a different chemical makeup – it tends to cut similar to casein though it’s chip size is similar to Corian.  Juma also does not have any distinct odor when it’s sanded, unlike Casein (which smells like bone) or Corian (which smells like acrylic).  According to Atlas Billiard Supply, Juma is also FDA approved and can be used for smoking pipes and kitchen utensils.

Rosebud on Juma, scrimmed and inked with color ink.
Holds ink and oil paint well if left to dry.

How well does it scrim?

Juma stipples well, cratering only slightly when stippled deeply, unlike polyester.  It scribes well with a sharp tool, dusting on a long line rather than curling like ivory. Appears to be only slightly softer than ivory.

How well does it stain?

When polished, India ink and oil paint wipe off easily. If unpolished or only sanded to 400 grit the crevices will hold your pigment and make it look cloudy.  Scribed and stippled lines come out crisp and well defined if the pigment is allowed to dry. Colored India inks hold well also.

Originally posted in the Scrimshaw.com Newsletter on June 14, 2015. For the latest information, tips and templates, subscribe to the newsletter – it’s low-carb, no spam, and you don’t need dramamine!

Sealing Bone Scales – Take 2

Last time, we tried just filling the voids in the bone scales with wax. This gave us spotty results – literally. Working with a couple of different formulations of cyanoacylate, we’re at the point of – still looking.

Loctite Plastic bonding with separate accellerator pen
Good for intended purpose, not so much for ours.

We attempted to follow the luthier’s method of building up the material with the bone dust from sanding the bone smooth and used  Loctite Plastic Bonding System which had an “accelerator” in the form of a marker made for gluing difficult materials.  This didn’t work well at all.

Loctite Super Glue
Liquid – not gel. Wear safety goggles as the vapors burn your eyes!

Next, we attempted to use some more off the shelf superglue – Loctite Super Glue LIQUID (not the gel, as we want this to seep into the cracks and fill them in). Piling the bone dust up and squirting the glue on made – a mess, though it might look better once it’s sanded down.

 

 

powdered bone and superglue on the left, just liquid on the right
Powdered bone on the left, liquid alone on the right

 

While we were waiting we looked at the other side of the bone and decided to just lay the glue straight down on that side to see if it worked any better.  My thoughts at the moment are that either (1) the bone dust is too fine and can’t saturate well (like lumps in the pancake batter when you make it from scratch) or (2) I need an even slower curing superglue.

 

 

After letting it dry thoroughly, I proceeded to sand down both sides with 220 grit sandpaper, followed by 600, 1000, 1800, 3200 and finally 8000 grit pads.  Wiping some oil paint across the whole piece and wiping it off, I find that the bone dust side is just as bad or worse than the untreated area (center), but the right side where we used no dust is looking pretty good! After 30 minutes the glue is still somewhat soft for scrimshawing. I’ll be testing it for “scrimmability” later in the week and will update my findings.

 

Left=superglue alone, middle - no glue, right glue and bone
Here, the liquid alone was on the left, the “naked bone” in the middle, and the powdered bone/superglue on the right after sanding. the “clear” winner so far is the plain superglue

 

 

1/4″ Corian Sheets from Inventables

Corian Sheet thicknessCorian sheet 10" x 12" fresh from InventablesSome of the joys of living rural include having bear, moose and coyote traipse through your yard and sample your garden, send the dog into chaotic spasms of barking and howling and having neighbors farther away from you than you can throw a rock (unless you sneak up on them). The downside is unless you know what delivery service your vendor is going to use and the exact address they have for you in their database, your material can come maddeningly close to your house only to get shipped back halfway across the United States.  This is what almost happened to the corian (pronounced “CORE-ian”).  If you use the people in the brown trucks you need to be sure the street address starts with “S.” and not “South”.  If it’s the people with the eagle on their shoulder, it’s another matter altogether.  Fortunately our USPS employees are friendly and helpful, and held the package for me as I raced down to pick it up.

"Bone" colored corian sample (1/2" thick) sits atop the white 1/4" thick sheet of Corian
“Bone” colored 1/2″ sample scrimshawed atop the white 1/4″ sheet

Corian is actually a mixture of acrylic and alumina trihydrate – which is refined from bauxite to a fine white powder and makes the material opaque.  By adding other colorants and materials a whole host of textures can be created.

It can be difficult to get Corian in the colors you want, since you usually need to pick up a full 48″ x 96″ sheet.  Instructables has black and white, though if you hunt around on eBay you can find smaller pieces from suppliers in many different colors.

As the material is acrylic with a powder in suspension, it tends to dust rather than curl even with an extremely sharp tool when you scribe. When stippling it doesn’t crater like polyester, making this technique a viable means of creating an image too.  Jigsaws and “rotozip” tools cut through it well, just don’t have the speed too high or you will melt rather than cut and make a big stink.

As in previous tests, India ink appears to work the best, oil wiping out easily unless you let it set for several days to a week.  Nick Finocchio regularly uses Corian, while others such as Katherine Plumer have used it on occasion.

Corian Cab set in antique barrette setting - top  Buying two sheets from Inventables will bring the cost down to about $0.46 per square inch in the US, while if you can find ¼” sheets on eBay it can drop to $0.14 per square inch and sometimes less and in a variety of colors, patterns and more.

side view of corian cab in antique barrette setting showing the thickness.  We had purchased the 1/4″ sheets in hopes of being able to cut and polish the material without much further prep work in order to use it as jewelry cabochons.  As you can see in the pic, they’re a bit too thick still to be used as such, but this thickness would be perfect for domed cabs and for knife handles, as well as for display pieces, thicker inlay work and more – coasters, ornaments… any other ideas for projects with 1/4″ Corian?

Casein “Plastic” for Scrimshaw – an Excellent Ivory Alternative

We have been working with a sheet form of casein for several months now and so far it’s the best alternative material we’ve found.  Made in England, the material comes as either one extremely large sheet, or the company is kind enough to quarter it so you can save on shipping, plus it’s easier to handle.

Rounded corner of casein sheet showing slightly rough edge
Rounded corner of casein sheet

 

Each quarter sheet comes with one rounded corner and one side that is rough and one side that is smooth.  Out of the box it is not scrimshaw ready, but it does sand and polish easily, giving off a bone-like smell when cutting and sanding. I’d asked for a material safety data sheet and they had sent me something similar which I may be able to dig up if you need.

When it comes to scrimming, it is about as dense as ivory and scribes easily once you’ve sanded and polished it. It takes both ink and oil paint very well, and sharpies tend to stain.

Like most sheet-form materials, this should be stored laying flat. I didn’t do this and came up with warped material after about five months. Laying it flat will allow it to settle back down.  All of my material began to get a slight bow to it with the exception of the paper micarta.  Interestingly, the material scorches easier than some of the plastic, but doesn’t catch fire if you put a flame to it.  I had a couple of thin scraps along with some pyralin which is pretty close to cellulose nitrate. The acrylic and pyralin burned, pyralin quite fast, but the casein just went out with a scorched end. I also tried doing an “iron on transfer” using an image created on a laser printer to see if that would work (I think it was the day I was wearing my lab coat: whenever I’m wearing it the dog runs off, my wife sets the extinguisher near me and says she’s going shopping with the kids).  The initial cost may put some people off, but it’s a lot of material: one sheet is 40cm x 50cm (15-¾”x19-½”) – cut down as I’d gotten them they’re an easily handled 20cm x 25cm (7-¾”x9-½”).  I tend to use a scroll saw to cut the roughs out then sand them to their final shape. Much harder than other companies poly “ivory alternative”, it’s worthwhile to start with a sharp blade.

quarter sheet of casein with ruler at the bottom.
One quarter sheet of casein

 

Our initial purchase cost us a bit over $100, and we’re just about in need of another order (I had sent ¼ sheet to a friend of mine to test but family matters and other obligations have taken precedence), so I’ll be reordering again.  Emailing an enquiry or phoning them, GPS is always pleasant and friendly to work with. The material is available in sheet, rod and bar form depending on your needs.

You can see their offerings at these two sites:

http://gpsagencies.co.uk/casein

http://www.ivoryalternative.com/pages/otherproducts.html

They offer many different materials for luthiers, knifemakers and craftsman.  Let them know scrimshaw.com sent you.

This article was originally posted on January 31, 2015 in the scrimshaw.com newsletter.

Corian: Ivory Alternative

Originally Posted in the Scrimshaw.com Newsletter 2014-09-14

Corian is a material most often used for countertops and sink tops made by DuPont.

The material is an acrylic polymer mixed with alumina trihydrate (ATH). ATH is suspended throughout the material giving it a uniform color.  They are able to create patterns as well, from a pebble-like surface to granular in appearance.

Being a stain and abrasion resistant material, it offers benefits and challenges to scrimshanders.

Corian polishes to a high lustre with progressive sanding and polishing and you can create an almost mirror-like finish if you take the time (see notes at the bottom for a link to polishing pads that go progressively to 12,000 grit).

Finding Samples of Corian

Samples are often available at big-box stores such as Home Depot and Lowes in the states, but they don’t just hand out free samples, you have to have a genuine interest in the material to make it worth their time. If you are or have a larger project in mind, you may be able to ask for some 2″ x 2″ blocks of the type you intend to scrimshaw on and they may give them to you. If you really just want some of the material for scrimshaw and don’t want to “shuck and jive” the sales person there are a couple of other options:

  • You can find a place that makes custom counter tops in your area and see if they either have samples or scraps they’re willing to part with (otherwise the waste material goes into landfills)
  • You can visit Dupont at http://www.surfaces.dupont.com/ and navigate to the place that allows you to get samples
  • You can purchase a sheet of corian from https://www.inventables.com/technologies/white-corian for about $27 as of the time of this writing.  We’d recommend going with the ¼” unless you’re making knife handles or pens.
  • Look on eBay – search for corian ¼”

 

There are several scrimshaw artists that are already using corian for their art, including:

Nick Finocchio (https://www.etsy.com/shop/ScrimshawEverything),

Dmitri Burakov (https://www.etsy.com/people/BDSart?ref=owner_profile_leftnav),

Katherine Plumer (http://www.katherineplumer.com/scrimshaw/closeups/fine_art/jessie.html)

and others.

 

Pigment Tests

We sanded then polished our sample with 600 grit, 1000 grit, 2000 grit sandpapers then polished it with the HUT PPP wax polish and let it sit for one day. Having misplaced the Sharpie pen (which I recall does stain the material), we instead used India ink, an Aquarelle pencil and oil paint.  All wiped off cleanly.

 

Stipple and Scratch Tests

For the stipple and scratch tests, we used our favorite Coulter tungsten scribe, and lightly stippled and scratched the surface. We found the material tends to “dust” more than crater with a light touch, and with the scratch tests it once again “dusts” rather than curl or create “rows and furrows” like some of the softer materials. Still the material seems softer than casein or ivory, probably due to the physical makeup of powdered ATH suspended in acrylic.

After hastening the drying time slightly with a blow dryer (the oil paint was still wet) we carefully wiped the sample away.

India ink is the clear winner here, the aquarelle pencil tended to ride above the scratches, though held well in the stipples and the oil paint wiped out of the stipples and scratches fairly easily, leaving little pigment.

Stain Test - Corian.jpg

Stipple and Scratch Test - Corian.jpg

A Tip from One of Our Readers:

“Hi Andrew,

I was reading with great interest on how to seal the items you sent me.

I remembered that I used a similar process when I was turning wood and pens.  Whenever I found a soft spot on antler or wood, I would fill it with a thin glue and use an accelerator to harden it and continue cutting.  I used some of this thin glue on one of them, let it soak in good and used the accelerator to harden the glue and then sanded it down up to 12,000 grit.  It looks great and will be ready when I get a little better at scrimming.

Here is a site with some info on the glue:

http://www.woodcraft.com/category/3/1005233/1001221/Glue%20and%20Glue%20Accessories.aspx

As I said, this was just a thought I came up with.

Have a wonderful day.

George Hester – Newbie but getting better”

 

Thanks again George, we’ll have to try the accelerator on some antler or bone the next time we get a chance.

Found another use for “Poster Putty”.  We’ve been using it to hold scrimshaw material in place as we scrim, but when it comes to inking the little vials I like to mix them in often end up sideways (which is why I’ve been banished from the kitchen table for all things non-food).  A small dab of poster putty will hold the vial or anything else spillable fast, even if you bump into it.  Available at most pharmacies and at Amazon.com.

Tipped ink vial (left) and one with poster putty on the bottom holding it fast.

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