"Grain" pattern in Tenite?

[MaximRecoil]

I recently got an all-original black 1958 Western Electric model 554, and when I was polishing the shell with Novus #3 followed by #2, I noticed the plastic had a wavy pattern in certain areas that looks similar to woodgrain. It's not really noticeable unless light is reflecting off it just right.

At first I thought the Novus may have caused it somehow, even though I've polished quite a few phones with Novus, including one other black Tenite one, and I've never seen a grain pattern in any of them. Then I took a closer look at the eBay seller's auction pictures and the grain pattern can be seen there too; it's just hard to notice unless you're looking for it because of all the scuffs and scratches it had. After polishing it became more noticeable.

The first picture is mine, taken after polishing. It's hard to get a good picture that shows the grain pattern, but it can still be seen (bottom half of the shell). The second picture is the seller's auction picture, and the grain pattern can be seen there too if you look closely.

Is this a known thing with Tenite or is mine just an anomaly?

[TelePlay]

Can you see the pattern in the same place but inside the housing?

All molded plastics start out as small colored pellets mixed together to get the desired plastic color. That can be seen in work phones. Yours may be a slightly incompletely mixed batch of pellets. That would be intentional making your phone a rarity.

[MaximRecoil]

Can you see the pattern in the same place but inside the housing?

No, I can't see it at all anywhere inside the shell.

On the outside of the shell I can see it on the lower half of the front side (which is where it's most prominent), all along the right-hand side, only a hint of it in a small area on the left-hand side, all along the bottom side, and none at all on the top side nor on the upper half of the front side.

Polishing makes it more visible, so I don't know if it would show up on the inside of the shell if that were polished or not (I don't want to polish the inside to find out because that would be a big job and it isn't supposed to be polished anyway).

[countryman]

The effect might come from sunlight (UV). As TelePlay said, pellets are heated and pressed into a mold to make these thermoplastic parts. Different batches of pellets, although of the same type, might show different reactions to UV over time. That would explain there is no grain visible on the inside.
I would not call this a fault, but patina.
Is it actually Tenite (Cellulose acetate butyrate, with the characteristic cheesy smell), or a more modern compound already?

[MaximRecoil]

Is it actually Tenite (Cellulose acetate butyrate, with the characteristic cheesy smell), or a more modern compound already?

It looks, feels, sounds, and polishes like Tenite, and the date printed on the inside of it is 8-8-58 (every part in the phone with a date on it is from August 1958). As for the cheesy smell that people often mention, I've never been able to smell it, not with this 1958 shell nor with my other black Tenite 554 shell from 1957 (7-21-57). They both just smell like Novus to me.

All the rest of my Western Electric phones are newer 500s, 554s, and 2500s from mid 1966 and later, which have ABS shells, which is a very different type of plastic. Aside from the differences in look, feel, and resonance, ABS is much harder to polish.

As for sunlight, it seems strange that it would have the grain on the bottom side (the side the handset cord exits from), where you wouldn't expect much sunlight to ever reach, but no grain on the upper half of the front side nor the top side. I suppose the areas with no grain could have been homogeneous to begin with.

Here's another picture that shows how it's only really noticeable when a certain amount of light is reflecting off it. If light isn't directly shining on it, it just looks black.

[LarryInMichigan]

I see that appearance all the time on tenite.  I assume it has to do with the nature of tenite.  I don't expect that there is anything that can be done about it.

Larry

[TelePlay]

I don't expect that there is anything that can be done about it.

No, it is what it is, how it was mixed (colored pellets used), how it was mixed when melted and how the pellet "colors" may have changed over time.

Chromophores are molecules in plastic that absorb and/or reflect specific visible light wavelengths.

Black is the absorption of all visible light. White is the reflection of all visible light. What you are seeing is a pellet color, that was mixed in with the other plastic pellets, that is reflecting some light and that pellet was not thoroughly mixed in with the other pellet colors designated by the engineers to get the "black" they wanted for those housings.

You're seeing those lighter pellet as striations or waves. Back then, 70 years ago, I'm sure they were happy with what was coming out of their molds, it was good enough to assemble and ship.

[MaximRecoil]

I don't expect that there is anything that can be done about it.

Yeah, it's definitely in the plastic to one degree or another, and I wouldn't be surprised if it could be seen on the inside of the shell if it were polished. I don't mind it; I was just curious about it because my other black Tenite shell from 1957 doesn't have it. It reminds me of polished ebony wood, which often looks solid black until you shine a light on it and see a grain pattern in it.

[countryman]

As for the cheesy smell that people often mention, I've never been able to smell it, not with this 1958 shell nor with my other black Tenite 554 shell from 1957 (7-21-57).

Its definitely there on my (1949) 302 - the individual perception may vary.
But apparently Eastman Kodak used the Tenite brand for different formulas or compounds based on cellulose acetate, butyrate or propionate or mixes of them all. The presence of the smell may have been reduced or even removed while it is still "Tenite"
A funny observation: The English Wikipedia has different articles for Tenite and for CAB (cellulose acetate butyrate). The former more emphasizes the perishability of the material, while the latter points out it's durability. Like they were talking about completely different things.

CAB is still used for niche products like quality tool handles for it's comfortable grip and mechanical strength, so I more tend to believe the latter article. The issues with the film spools mentioned in the first article may have their own reason, maybe added softeners?

[MaximRecoil]

Its definitely there on my (1949) 302 - the individual perception may vary.
But apparently Eastman Kodak used the Tenite brand for different formulas or compounds based on cellulose acetate, butyrate or propionate or mixes of them all. The presence of the smell may have been reduced or even removed while it is still "Tenite"
A funny observation: The English Wikipedia has different articles for Tenite and for CAB (cellulose acetate butyrate). The former more emphasizes the perishability of the material, while the latter points out it's durability. Like they were talking about completely different things.

CAB is still used for niche products like quality tool handles for it's comfortable grip and mechanical strength, so I more tend to believe the latter article. The issues with the film spools mentioned in the first article may have their own reason, maybe added softeners?

The stuff Western Electric used for early black 554 shells (and presumably early black 500 shells too, though I don't have any of those) seems to be plenty durable, considering how many of them still exist after 70+ years with no cracks nor noticeable shrinkage/warpage. It does scratch easier than ABS does, but it's also easier to polish out the scratches. And I like the look, feel, and sound of it a lot better than ABS.

[TelePlay]

About 2.5 years ago, someone asked how they could test a 554 housing to see if it's soft plastic or ABS plastic.

I did some testing and posted this:

If you put a small drop of 70% Isopropyl Alcohol on a clean area inside the case and let it dry by itself over several minutes, if it leaves a ring in the plastic that can be felt when running a finger tip over the spot, it's soft plastic.

If it does not, it's ABS, hard plastic.

It's a valid, easy and simple test in that soft plastic is dissolved with isopropyl alcohol and ABS is not at all affected by alcohol.

[countryman]

Correct, Tenite (CAB) can be chemically sanded using alcohol including ethanol (rubbing alcohol, denatured alcohol). That's how I improved my 302 which arrived in very poor, scratched condition. ABS or polystyrene won't be affected by alcohol, but by acetone.

[MaximRecoil]

About 2.5 years ago, someone asked how they could test a 554 housing to see if it's soft plastic or ABS plastic.

I did some testing and posted this:

It's a valid, easy and simple test in that soft plastic is dissolved with isopropyl alcohol and ABS is not at all affected by alcohol.

Yeah, I found that out the hard way with my 1957 shell many years ago, before I'd ever even heard of Tenite / "soft plastic." I'd always cleaned my newer Western Electric phones (ABS) with isopropyl alcohol, but when I started to do it with that 1957 shell, it damaged it almost immediately. Then I researched it online and found out about Tenite.

Fortunately, it wasn't a very good shell to begin with. It had been "modularized" and because the square notch they'd cut into the bottom for the modular jack created a stress riser, a crack had developed in the corner of the cutout. I super glued it back together many years ago (before the alcohol incident) and it's still holding. On top of that, it had been over-polished before I got it, most likely on a buffing wheel, and it was part of a "Frankenphone" (a mixture of Western Electric, Northern Electric, and ITT Kellogg parts from wildly different dates). I was able to fix the alcohol damage with sanding and polishing with Novus.

But after you're familiar with both Tenite and ABS, it's easy to tell them apart just by the look and feel of each one.