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Tuesday, June 21, 2011

Telling The Difference Between Bakelite, Ivory and Plastic


Between 1907 and 1909, Dr. Leo H. Baekeland was conducting experiments to create a varnish.  He was using phenol and formaldehyde, generally with wood flour filler, and put the mixture under heat and pressure.  He accidentally discovered bakelite.  It was the first plastic made from synthetic polymers.
Bakelite's properties were its hardness, durability, nonconductiveness, and heat resistance.  Once it was molded and cast, it could not be melted.  It was often called "The Material of a Thousand Uses."  A little known fact about bakelite is that in 1942, it was considered by the US Mint to make pennies due to copper's use during World War II.  Several designs were even made, but the bakelite penny stepped aside for the Steel penny of 1943.  The mint returned to recycled copper shell casings for the 1944 and 1945 pennies.
As costume jewelry, bakelite had its biggest boom in the 1930's during the Great Depression.  It was used to imitate tortoiseshell, coral, amber, ivory and other costly materials.  It was attractive to all levels of incomes, including the very rich.  Some designer bakelite pieces were made to sell to fine department stores in the $10 price range.  For the Great Depression, this was a phenomenal price for a piece of jewelry.  Those pieces were generally the brightest, most massive, and most highly carved items.  Due to their scarceness, they are the pieces that command the highest prices today.
There are many testing methods for bakelite, but not all are recommended.  Most recognized tests are:
    • Friction
    • Hot Water
    • Scrubbing Bubbles
    • Hot Pin
    • 409
    • Lemon Juice
    • Simichrome Polish

Friction Test
The friction test is most commonly used when you are at a flea market, yard sale, or antiques store and do not have access to other methods.  You simply rub the piece until your thumb feels hot, and sniff.  Bakelite gives off a very recognizable chemical smell due to the formaldehyde.  In other words, it really stinks.  Do NOT get confused with the smell of attic, or dirt.  The only way I can personally describe it is you feel a "headrush" right between your eyes from the chemicals.
This test does not always work, of course.  It greatly depends on how well the piece was kept and stored.  Unfortunately, sometimes this is the only test you have the option of performing.

Hot Water
Similar to the friction test, in that you are trying to find the tell-tale smell of formaldehyde.  You hold a part of the item under very warm water for about 10-15 seconds.  Then smell it!  If the initial response is to grimace, and pull it away from your nose immediately, it is bakelite!
This is one of the most successful tests for Bakelite, but again, it is not fool-proof.  If the piece was newly polished, carved, or is highly dirty, you may get a false-negative.  Also, if a non-bakelite piece has been recently dyed or shellacked, you may get a false positive.  Also, beware of getting findings wet, as glue or other adornments could become weak.

Scrubbing Bubbles
Dow Bathroom Cleaner was often suggested for testing for Bakelite.  When a portion of the piece was rubbed with Scrubbing Bubbles, you would get a tell-tale yellow streak, regardless of the color of bakelite.  However, this method is highly discouraged, as it has harsh chemicals that strips finish, and can make a nice shiny surface dull and lacking luster.

Hot Pin
This is another test that has been strongly discouraged!  The purpose of a hot-pin test was to take a pin that's tip has become red from a flame, and touch the tip to the piece.  The characteristic of bakelite makes it not melt.  However, there would be a dark, unsightly mark on where the piece was tested.  This greatly decreased the value of the piece.
This test was also preferred to test pieces of bakelite that appeared to be amber.  Amber gives off a faint pine-scent when touched with a hot pin.
Further difficulties of this test are that thermoset plastics also do not melt, which could confuse someone into thinking the item was bakelite!  Furthermore, if the piece of jewelry was celluloid, not only does this melt, it combusts easily!  You could easily burn yourself with dripping, flaming plastic that will not easily come off your skin or clothing!  People had been hurt and wound up with disfiguring scars.

409
409 has become one of the more widely acceptable tests.  It has replaced the scrubbing bubbles testing method.  If you soak a cotton swab in 409, and rub the piece, you will get the tell-tale yellow mark that ranges from pale canary yellow to more orange/yellow.
The downfall to 409, is a lot of people will confuse DIRT, or dirty pale brown, for yellow and get a false-positive.  409 does not strip the finish of the piece, but still always test on the back.  Also, clean the area with mild dish liquid or hand soap and warm water.  Dry with soft cloth.

Lemon Juice
Lemon Juice will not test for bakelite, so to speak.  However, bakelite was often made to look like coral.  A test to tell if a "coral" piece is plastic or real (and then to resume other tests) is to drop a small bit of lemon juice on it.  If it becomes effervescent, it is *real* coral.  If it does not bubble, resume other testing methods.

Simichrome Polish
Simichrome Polish is generally said to be the "expensive" method of testing for bakelite.  It is a pale tannish pink paste and is highly valued for its polishing qualities!  Not only is it great for polishing metals, it restores finish to bakelite and other plastics!  You can simply polish the piece, and check the soft cloth.  If it has the yellow, it is bakelite!  Be careful of the "dirt" false-positive, that is also familiar to the 409 test.  If it's not bakelite, you still have improved the appearance and possibly value of the piece!

Some real ivory has grain that is very difficult to see with the unassisted eye, a 15-20x loupe is a tremendous help - celluloid/Bakelite does not tend to get check-cracks that are long, normally they'll be short (0.150" or less) and erratic whereas bone & ivory .  Depending on the storage/use conditions Bakelite/celluloid may not produce a readily detectable "old Lionel xfmr smell" (excellent analogy Nate) with the finger-rub test.  You can also do the "feel" test, at room temperature, ivory will feel cool to the touch and plastic will feet warm.

Don't be quick to toss something that is plastic because depending on the item and sometimes the specific type of plastic, it may actually be worth more than it was real ivory.

Here's some info from a website:
How do I tell if something is ivory, bone or an ivory substitute (plastic or resin)?

Ivory is actually the natural tooth of an animal. Teeth continue to grow throughout an animal's lifetime and as a result, they have a noticeable structure and "growth lines" (called Schreger lines in elephant ivory). Look at the piece carefully under a magnifying glass. Under a 10x magnifier, elephant and mammoth ivory will have visible striations or grain that often show up as diamond or "V" shapes or cross-hatching on the surface or edges of polished ivory. Bone lacks such "V" shaped striations. Under magnification bone usually shows minuscule circular or oval shaped dots on cut surfaces. These dots are the tiny vessels that once supplied the living bone. Also, bone exhibits grain-like parallel striations and usually has dark flecks of dirt particles caught in the pores of cut bone -- all not present in ivory. Resins or plastics have a uniform surface, usually with no striations or diamond or "V" patterns, however some manufacturers are now introducing faux ivory with an attempt to reproduce some of these features.

When looking at a piece, check the bottom or sides for the diamond or cross-hatch pattern typical of real ivory. Then check again for a slight wood-grain pattern, this is also typical of real ivory. Next, check the feel. Real ivory should have a cool-to-the-touch feeling. Resins or plastics may duplicate one or some of these features, but none duplicates them all.

Also, color often varies slightly (I emphasize slightly) throughout natural ivory (more variable in mammoth) from a creamy white to a creamy yellow-tan or a creamy, light yellow-brown, whereas bone and plastics are either consistent in color throughout, or their color variations may be extreme, especially in stained or colorized resins and plastics.

The next test involves using an inexpensive blacklight which you can find at most department or home improvement stores. Shine the blacklight on the piece. Ivory develops a beautiful natural patina with age which shows up as a yellow-brown overall color under normal lighting conditions. Under ultraviolet light, where the original ivory surface shows through the patina, the ivory will show up a bright white. When ultraviolet light is shined on resin or plastic ivory substitutes, the ultraviolet light is absorbed and they exhibit a dull appearance. (The light emitted by many long wave ultraviolet radiation lamps is hazardous to the eyes. NEVER look directly at a UV light.)

You can also take a Q-tip, dip it in alcohol and rub the piece in an inconspicuous area. If the patina comes off and colors the Q-tip, chances are good it's paint or varnish or some other substance that was applied to give the impression of age.



3 comments:

  1. Fascinating. Thank you. I bookmarked and will refer to this, particularly the ivory/bone info.

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  2. A GREAT reference piece, Sharyn...I'll definitely be referring to this as well...thanks
    : )

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  3. You know, you and Helen are going to have me out buying everything in sight! Thanks for the information Sharyn :)

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