Old Game Plastics Restoration

Plastic Game Restoration

Plastics are everywhere today, and without them most of our modern technology would not exist. Yet the development of the first plastics was driven by very specific, even mundane needs of the time. As a new middle class emerged with disposable income for leisurely pursuits and luxury items, demand for ivory increased. This fueled the search for an artificial substitute – celluloid. Casein (Galalith) was developed during the search for a better blackboard material.

Leo Baekeland’s interest in photographic materials led to the development of Bakelite. The enormous potential of these early compounds was obvious, and after only a few years they were found everywhere. Buttons, vanity items, knitting needles, utensil handles, telephones, board game parts, and pieces for tile games, board game parts, and other classic games pieces all were made from plastic. And now the middle class could enjoy what only the wealthy could before.

How to indentify plastics

Unless you have a mass spectrometer in your basement, identifying plastics requires a little background. Here are just a few rules:

• if it floats in water, it is either polyethylene or polypropylene
• if it has a metallic “clink” it’s probably polystyrene
• if you are willing to burn some of it with a soldering iron or match, you can get a lot of information. Texloc has a great chart covering most of the modern plastics and some of the vintage plastics.

The Smell Test

The most reliable way to distinguish vintage plastics, short of the mass spec, is by scent, but it takes a little experience. You can rub a piece firmly with your thumb to heat it until it emits an odor. Hot water works very well on buttons, bangles, etc, but use with caution on Mahjong tiles – it can lift the paint. It’s a little harder to get a scent from casein – you can use very fine sandpaper (6000 grit) to heat it enough to smell it.

Bakelite and Catalin have a very distinctive smell – a sweet chemical odor. Once you smell it once or twice, you can recognize it easily. If you haven’t spent much time at the chemistry bench, find a piece that you know is bakelite, or confirm by other means (see below), and get familiar with the scent.

• Celluloid is made with camphor, and will smell like mothballs or pine sap.
• Casein is made with animal protein, and smells, unfortunately, like wet dog.
• Lucite and Plexiglass are odorless.

Phenolics: catalin and bakelite

As bakelite and catalin age, UV light causes a layer of phenyl alcohol to form on its surface. Phenyl alcohol is yellow-brown, so it imparts that tint to the original color. Thus cobalt bec=omes “blue moon” to olive green (see photo below), bright red becomes mahogany, white becomes butterscotch. Phenyl alcohol is an excellent sunscreen, so the discoloration only penetrates a millimeter or so. These plastics are very resistant to chemicals, and will never melt or ignite. Catalin, however, will shrink over time. This can result in warping and cracking of the piece.

Celluloid

As we mention in care and repair of plastics, celluloid is prone to significant changes with age. It can yellow with time, turn pinkish-brown, crumble, and implode.

Casein

Casein can lose moisture over time, and sometimes you can see this as a subtle “crinkle” on the surface. Our casein Mah Jong set doen’t show this, however, and so far appears to be pretty bulletproof.

Other Tests

On exposure to UV light, catalin and bakelite form a layer of phenyl alcohol. This is responsible for the change in their color with age. Cleaners such as Simichrome polish, 409, or Scrubbing Bubbles will remove a bit of this phenyl alcohol, imparting a yellow tint to your cotton swab. This phenyl alcohol means that vintage bakelite is never white.

One foolproof way to identify celluloid is use of acetone. It will dissolve celluloid completely. I don’t recommend this as a routine method of identification.

Visual Clues

Thin pieces of casein plastic develop a subtle crackle texture as they gradually lose moisture (Fig. 4). Celluloid can be almost white (but not quite). In game pieces it may be in french ivory form – darker and lighter sheets compressed together to imitate ivory (Fig. 5). When it discolors with age it can yellow or take on a pinkish brown tone. Catalin is variably translucent, and typically swirled (Fig 6). Later plastics imitated this look, but don’t have the dense, almost stone-like feel of the phenolics.

Care and Repair of Vintage Plastics

Celluloid is subject to degradation via heat, acids, alkalis, and UV light. It can quite literally disintegrate when kept in poor conditions. The most harmful environmental agent is moisture, as water is required for all of the aforementioned chemical reactions.

To take care of your plastic pieces you should:

• Keep your celluloid game pieces in a cool dry location and ensure good air circulation.
• Consider adding packets of silica desiccant to game cases containing celluloid pieces.
• Use a cloth slightly dampened with either water or isopropyl alcohol when cleaning (only do this if cleaning is needed). Make sure to dry carefully afterwards.

Bakelite holds up well over time. UV light causes it to discolor over time, but that discoloration is superficial. Catalin shrinks over time, which is why Catalin radio chassis will warp, and translucent and enrobed Mahjong tiles are susceptible to cracking. Both can be cleaned with water, but when cleaning Mahjong tiles it is advised to use isopropyl alcohol to avoid damaging their paint.

Disclaimer: we do not have a degree in conservation. Below we describe what we have learned informally and through trial and error. If you have something really valuable that needs restoration, take it to a professional.

How do you repair bakelite/catalin?

It is recommended to use slow-setting epoxy with good flexibility for phenolic plastics. This should accommodate catalin’s shrinkage over time. Epoxy can be tinted with acrylic paint to color match the material, then by sanding and polishing, you can have a near-invisible repair (see pictures here).

How do you repair Celluloid?

You can use Duco cement (nitrocellulose) to re-glue celluloid (cellulose nitrate) faces that have delaminated from hardwood Mahjong tiles. You can also use acetone or celluloid dissolved in acetone as a glue for celluloid. The second option could be a bit trickier, so make sure you know what you are doing.

How do you restore old adhesives?

Mahjong and other game cases are typically constructed of dovetailed wood sides and cardboard. The joints are glued, and the covering applied with hide glue. Hide glue softens with heat and moisture, so it is unusual to find paper-covered cases intact today. If covered in oilcloth, they tend to hold up a bit better.

To repair old cases:

• Use wood glue for the frame.
• For the covering use a mixture of wheat paste and PVA – very similar to that used by bookbinders.

How do you restore new adhesives?

For plastics, Duco cement (nitrocellulose) should be the best for celluloid (cellulose nitrate). The method used by guitar makers is to dissolve celluloid in acetone and use that mixture as an adhesive. Which is a little bit too tricky in our opinion. For other plastics, especially Catalin, you can use a slow-setting epoxy with good flexibility.

Catalin vs Bakelite

What are Catalin and Bakelite?

Strictly speaking, Catalin and Bakelite are both trade names for the same compound: phenol formaldehyde. However, the terms are often used to distinguish cast phenolics (Catalin) and molded phenolics (Bakelite).

Which terms are used largely depends on the circle in which you run:

• Radio collectors refer to the brightly-colored cast phenolics as catalin, despite the cast radio parts being manufactured by the Bakelite Corpotation, the Catalin Corporation, Marblette, Monsanto, and Knoedler.
• Vintage Mahjong collectors refer to opaque game pieces as bakelite and more translucent or swirled pieces as catalin.
• Jewelry collectors refer to all phenolics as bakelite.

Below, to avoid confusion, we capitalize the company name and leave the generic referral uncapitalized.

In “Plastics History U.S.A.”, a comprehensive history of the plastics industry between 1890 and 1950 by J. Harry DuBois, the Catalin Corporation receives little more than a footnote, despite a great deal of detail of the processes used to manufacture the phenolics, and the people involved in their development. After reading this book, one gets the distinct impression that the term “catalin” probably receives more use than it merits.

How is catalin and bakelite made?

In order to produce the molded phenolics (catalin and bakelite):

1. Phenol and formaldehyde were mixed and heated with an alkali catalyst.
2. The resulting resin was cooled, powdered, and mixed with a filler such as wood flour, powdered walnut shells, or asbestos.
3. That mixture was then placed into a heated, pressurized mold which produced the final product – telephone receivers, electrical parts, camera cases.

The original resin was amber-colored, and therefore this was best suited for darker plastics.

Bakelite Corporation was making a cast phenolic long before its patent ran out in 1927. A special interest of one of the company’s chief chemists was this transparent colored form, from which Bakelite Corp. made pipe stems, billiard balls, and jewellery. When the patent for Bakelite Corp. ran out in 1927, the Catalin Corporation, among others, began making their own cast phenol formaldehyde plastic.

To make a cast phenolic the initial resin was kept liquid, dyed the desired color, and poured into molds to harden with heat and hydrostatic pressure. By mixing different batches together, they could produce pieces with swirled or marbled patterns. The lighter color of this resin allowed it to be more brightly-colored and translucent.

What is the difference between catalin and bakelite?

• Bakelite: molded phenolics, by virtue of their filler material, are opaque, stable and very tough. They are resistant to chips and cracking.
• Catalin: cast phenolics are colorful, weaker, and over time can warp and crack.

We have looked at many Mahjong tiles, and they do give us pause. Some are obviously translucent, swirled cast phenolic. But the rest are variably opaque, and if you sand them down are light ivory inside. Most have had their designs pressed into the surface of the plastic. The light interior suggests casting, the pressed design and opacity suggest molding.

When it gets down to brass tacks, it seems no less accurate to call all phenolics bakelite than to make a distinction based on color or translucency. If you wanted to be strictly accurate, you would call everything either “cast phenol formaldehyde” or “molded phenol formaldehyde”. But we would get carpal tunnel syndrome from all the typing, and frankly, there is no need to be that precise.

Old Plastic Game Cases

It all started with an old Mahjong set whose case was quite literally falling apart, held together by nothing more than packing tape. We thought it would be a shame to throw the case away – the wooden sides were intact, the top and bottom boards were there, and the hardware was actually in good shape. We didn’t take “before” pictures, but you can see how that first case turned out below. Then came the second, and the third, the technique changing a bit each time. Below, see some vintage plastic game cases and more.