Unsticking ivory/bone threads that are stuck

I've got an ivory [or bone] container with a screw top threaded lid. The lid is stuck on. Is there anything that can be done, that will not damage the material, to get it unstuck?

 

Do you know what it originally contained? That might give a clue to selecting a safe and effective solvent or lubricant.

 

What’s the top made of?

 

The whole container is bone/ivory. Sort of looks like an egg. Very small, about 15mm tall. It's supposed to contain very small dice, 2mm+/- cubes.

 

May we see it, please?

 

This is the same container, but opened.

 

If it’s not valuable you could try mineral oil with an eye dropper and let it sit with the threads downward. I’m not an ivory expert but some google searches indicate mineral oil is compatible and can be wiped later with alcohol

 

"Valuable" is subjective. We've seen these sold, with their original contents, for $100 each.

The 'eggs' are hand painted, so that's an issue. We have a few of these, and all but one has the seam between top and bottom so tight I don't think mineral oil would penetrate.

I've done more reading, and I'm going to try a hot, damp, cloth on the top half, hoping that the heat will expand it just enough to let it spin.

 

Good old sewing machine oil would be my first stop as long as the egg isn't painted. It's a super-fine grade of oil meant to lubricate an old school sewing machine. I have it because my machine is older than I am. Not sure what it would do to bone though.

 

I'll look into that oil. Half of the pieces that I have are hand painted...

Edit: Update: Whelp that's the end of machine oil:
Applying sewing machine oil to carved bone can cause significant and potentially irreversible damage, including discoloration, weakening, and odor.

Apparently mineral oil is used on ivory and bone to strengthen the material. I'll have to get some.

 

Good luck. Will you let us know the result?

 

You may try to tightly wrapp small rubber bands around each half to get a better grip and try again to unscrew manually with some force.
I cross my fingers for you, good luck!

 

Here's another picture to show how small they are

 

Look at a food grade mineral oil. Also, consider Ballistol, with is a mineral oil/water emulsion for guns/wood/leather. It doesn't stain leather or wood.

 

Could it be tagua nut?

 

I was wondering the same. The pitting looks more like tagua nut than bone, which is more likely to crack.

 

The nuts are at least partially hollow to start with too, and it's the right size. I'd love to mess with it in person.

 

I asked Google AI:
how to open a stuck tagua etui?

Opening a stuck tagua etui requires a gentle touch to avoid damaging the delicate vegetable ivory, which can be brittle. Unlike a screw-top jar, an etui likely has a friction-fit or swivel-style lid that may be stuck due to changes in humidity, age, or dried-out contents.
Here are several methods, starting with the least invasive.
Method 1: Gentle tapping and rotation
If the lid is stuck because of dried residue or a minor misalignment, light tapping can sometimes help dislodge it.

1. Wrap the etui in a soft cloth or towel to protect it.
2. Gently tap all around the seam of the lid with a small, soft mallet or the wooden handle of a butter knife.
3. Apply firm but slow and steady pressure to try to swivel the lid open.

Method 2: Temperature expansion
Tagua nut, like other natural materials, will expand and contract with changes in temperature. You can use this principle to try to create a gap between the lid and the base.

1. Use a hair dryer on a low, warm setting to gently warm the seam where the lid meets the base. Heat causes the material to expand slightly. Be careful not to overheat it, as excessive heat could cause it to crack.
2. Use a freezer to contract the material. Place the etui in a sealed bag and put it in the freezer for about 30 minutes. The cold may cause the lid to shrink just enough to break the seal.
3. After either method, try opening the etui again. You can also alternate between gentle heat and cold for a more pronounced effect.

Method 3: Improve grip
Sometimes the issue is simply a lack of traction.

1. Use a rubber jar opener, rubber dish gloves, or a rubber band wrapped around the etui to get a better grip.
2. Hold the etui in one hand and twist the lid with the other.

Method 4: Use a wedge (last resort)
If the above methods fail, you can try to break the seal with a thin, dull object. This method carries a higher risk of scratching or chipping the etui, so proceed with extreme caution.

1. Use a very thin tool, such as a plastic pry tool or a butter knife.
2. Wrap a thin, protective layer, like a piece of paper or masking tape, around the tip of the tool to prevent scratches.
3. Carefully wedge the tool into the seam where the lid joins the body and twist it gently. The goal is to break the seal, not to pry the lid completely open.

How to prevent it from happening again
Once you have the etui open, you can prevent it from getting stuck in the future.

• Wipe the edges. Use a dry cloth to wipe away any dust or moisture from the inside edges of the lid and the rim of the body.
• Lubricate the seam. Apply a tiny amount of mineral oil, silicone grease, or a dry wax to the moving parts to allow for easier, smoother opening and closing. This will prevent friction from causing it to jam again.

Cautionary notes

• Do not use excessive force. Unlike a metal jar lid, a tagua nut etui can be brittle and crack under pressure.
• Do not soak the etui in water. Tagua nut can be damaged by moisture, and prolonged soaking can cause it to swell or warp.
• Avoid using sharp metal tools, such as a knife, for prying. This can permanently scratch and damage the surface.

For residue on a tagua nut etui, which is a plant-based material often called "vegetable ivory," it is critical to use a mild, gentle solvent that will not damage the porous organic material. Harsh chemicals can cause discoloration, cracking, or deterioration.

Safe solvents for tagua nut

• Mineral oil: The safest option is to use a small amount of mineral oil (or a gentle natural oil like coconut oil) applied with a cotton swab or soft cloth. The oil will help break down the residue while moisturizing the tagua nut, preventing it from drying out and cracking.
• Mild soap and water: A very dilute solution of mild soap (such as dish soap or Ivory soap) and water can be used sparingly. Use a damp, soft cloth to wipe the surface, and avoid soaking the etui, as excess moisture can cause damage.
• Rubbing alcohol (isopropyl alcohol): A small amount of rubbing alcohol on a cotton swab can be used to spot-clean stubborn residue. However, it is a stronger solvent, so test it on an inconspicuous area first. After cleaning, wipe the area with a damp cloth to remove any excess alcohol.
• Lighter fluid: Some sources suggest lighter fluid for removing sticky residue, as it is effective and considered safer on many materials than harsher solvents like acetone. Use with caution and test a small spot first.

Solvents to avoid

• Acetone (nail polish remover): Acetone is a very powerful solvent that is known to melt or damage plastics and can be too harsh for porous, natural materials like tagua nut.
• Bleach: As a strong chemical, bleach can cause irreversible damage, such as corrosion and discoloration, to organic materials.
• Turpentine: This is an oil-based solvent that can be very aggressive and may damage or leave a residue on porous surfaces.

 

I have to wonder just how many tagua nuts AI has tried to open.......

 

The guidance for tagua sounds pretty similar to that for ivory, both natural, porous substances.