Jump to content

What Causes Orange Peel?


Recommended Posts

  • Replies 86
  • Created
  • Last Reply

Top Posters In This Topic

Hot glass and cold rollers.

Marble surface temp cooling too fast on the rollers..

Less orange peel on smaller euro's because of the smaller

volume of glass is more forgiving than the 1 inchers.

Too large of a glass "blank" on the rollers makes footballs and eggs.

Just a guess,,,,,,,,

Link to post
Share on other sites

I believe the chemical composition of some glass can lead to "orange peel surface" when cooled at a certain speed. I also believe the quantity of glass can contribute to the way the glass cools which can contribute to whether "orange peel" forms or not. In other words, several contributing factors.

Link to post
Share on other sites

To All:

I think the definition of "orange peel" may vary from individual to individual (myself included).

Clarifying this may help in the discussion.

Photo samples would help.

Steph:

What Causes Orange Peel?

Since this is a marble chat board, I'm assuming you're referring to orange peel on spherical glass marbles as opposed to bottles, plate glass, car paint, etc.

Is it glass temperature and cooling rates?

Yes, kind-of, but let me develop this a bit more below.

Is it something more complicated like the chemistry of the glass involved?

I'm sure some chemical imbalance could be at play, but most glass formulae are well established.

I wouldn't rule this out, but I would marginalize it to the less than 1% category.

Bumblebee:

Rough rollers?

The definition of "rough rollers" can vary.

If you are referring to the commonly found pocked surface ("orange peel") of marble machine augers, then I can agree.

P8060175

It was my assumption orange peel happened due to surfaces on the marble machine, because I've only seen it on very large mibs. I figured the heavier big marbles while still malleable would gather these dimples by virtue of their weight. Just a theory, though.

I would agree with your general assessment, but let me run with it a bit more.

Hope we can all agree that small and large marbles can get orange peel, but why big marbles more than small ones?

A 5/8" marble has a volume of 0.12783 in^3.

A 3/4" marble has a volume of 0.22089 in^3 (1.73x larger than a 5/8").

A 1" marble has a volume of 0.5236 in^3 (4.1x larger than a 5/8").

A 1-1/4" marble has a volume of 1.02265 in^3 (8x larger than a 5/8").

[using glass with the same density, a 1" marble weighs 4.1x more than a 5/8".]

Just a guess but probably 90% of all marbles run are 5/8" with the remaining 10% of smaller and larger marbles (of which shooter 3/4" are included).

Large marbles (say over 3/4") are infrequently run, because they are expensive to produce and the demand wasn't there.

This meant that marble rounding machines for large spheres where mostly idle throughout the year.

Rounding augers are made of steel.

The environments of Illinois, Ohio and West Virginia vary wildly from Winter to Summer.

An idle marble machine would warm up from the heat of mid-Summer day.

As the sun fell and the air and marble machine cooled, the moist, humid summer air would condense on the surface of the augers.

This surface water would evaporate the next day as the temperature rose.

Little-by-little, oxides (rust) would form on the steel surface.

The rust doesn't form evenly, but becomes micro-localized and develops an orange peel surface.

https://abhsscience.wikispaces.com/Rusting+SB

When it comes time to dust off the large machine for a run, the operators have to decide how to clean the auger grooves.
Use a wire brush to knock off most of the rust on the surface, then run a bunch of glass through to get the remainder down in the little pockets/pits?
I'm sure people have seen the first marbles come off a new run and there is rust on the marble surface for a while.
The machine in the above photos is the Jabo machine at Wheaton Village before Scott Meyer reconditioned her.

P8060180

After the machine was rehabbed, they ran some samples across the rollers.

Those samples exhibit extreme orange peel.
Block auctioned a few of these and photos do exist (maybe someone can post?).
All small and large glass gobs are molten as they are delivered to the augers.
At the moment the gob touches the augers, the surface of the molten glass gets imprinted with the texture of the roller.
However, the weight of a large marble does force the glass against the roller surface more than a smaller volume/weight gob.
Larger marble=heavier weight=deeper impression.
Smaller marble=lighter weight=lighter impression.
Once imprinted, it can't be removed.
I like watching people run a torch across the marbles as they run down the auger in the hopes of rounding a marble or smoothing the surface.
The results of combusting gas (propane or other hydrocarbons) are CO2 and H2O (water).
Yes, hot water is being blasted onto the steel augers below.
And yes, surface rust forms instantaneously.
Those marbles will have a light copper looking rust on the surface.
I've got to run for now...
Sincerely,
John McCormick
"Shamrock Marbles"
Link to post
Share on other sites

The orange peel I am most familiar with is the type often seen on large Vacors. Under close examination it does not appear to be associated with dirty rollers but more like what happens to some paint as it dries. My scope is not working right now but when I get it going again I will post picture to show what I am talking about. In the mean time here are some roller marks on an absolute Wet Mint CAC.

post-87-0-75086800-1447556165_thumb.jpg

Link to post
Share on other sites

Alan:

Chilled glass, including rollers that aren't up to temp.

Can you elaborate a little more?

My rollers are run at room temperature.

Is there a certain temperature at which orange peel disappears?

Cheese:

I've also been told that if a marble is too big for the rollers it will get orange peel.

Yes, that is because the whole surface of the marble comes into contact with the roller.

But even, "right-sized" marbles can get orange peel imprints from the rollers.

Ann:

Sounds reasonable. But I seem to remember some smaller Euro sparklers with orange peel. In which case I'd have to go with the temperature thing. I'll check mine tonight . . .

Going back to the premise that lower production numbers of products smaller than 5/8" and larger than 3/4" result in tooling that sits idle and becomes rusty.

Add to the fact, that as general production decreased, even 5/8" machines were pushed aside into storage.

I'm sure there are a few people here that have walked through a marble facility and see machines sitting on the side in various states of decay.

Let's not forget about playing favorites.

Machine operators "know" which machines are less prone to down-time and produce the best product with the least hassle.

These are their "go-to" machines.

If something on this machine breaks, they usually steal a part off one in the bone yard.

Machines that are run more are broken in and don't have as rough rollers.

When production picks up and they have to pull a machine from storage, what do you think they choose?

Obviously, the best machine that runs.

Does any modern marble factory have a "surface standard" in their quality requirements.

Doubt it. Or they would be throwing away a lot of money.

They don't even care if they're round or chipped!

Orange peel is not even on their radar.

Hi John -- So is it glass temperature, but not related to the temp. of the rollers? Or something off in the glass mix, maybe?

Yes, one variable is about the glass temperature.

But most glass is delivered to a marble machine in a molten (pliable/plastic) state.

The fundamental purpose of the marble forming machine is to spin (on multiple axis) the hot, molten gob of glass into a sphere before it cools and it's shape is locked.

Roller temperature does play a roll, but so does the ambient temperature.

Even the temperature of the shearing device and any surface the glass comes into contact before hitting the augers.

(There are other variables at play also.)

Different glasses have different working times.

Spectrum cobalt blue gets stiff really quick, but the opaque white stays pliable longer.

But neither glasses have a chemistry that give an orange peel surface to a marble.

MarbleDawg86

I've noticed on practically all Peltier NLR's there is some degree of an orange peel on the surface, usually not noticeable unless under magnification. It's usually a good way to tell if one has been buffed:polished, as this will remove the orange peel.

You bring up a great point.

What orange peel are we talking about?

Severe enough to be easily seen with the naked eye (20/20) at 12" distance under X lumens?

I will concede that even minty marbles have imperfect surfaces under magnification, but are still a direct reflection of the marble machine surface.

Griff:

What kind of glass do you use,John?

Is it similar to the vintage,or something differant?

Moretti/Effrette, Spectrum, Bullseye, Kokomo, Youghiogheny, Wissmach, Uroboros, Spruce Pine, Kugler, Reichenbach and various cullet from Gabbert (Fenton red, etc.).

Galen:

The orange peel I am most familiar with is the type often seen on large Vacors. Under close examination it does not appear to be associated with dirty rollers but more like what happens to some paint as it dries. My scope is not working right now but when I get it going again I will post picture to show what I am talking about. In the mean time here are some roller marks on an absolute Wet Mint CAC.

I am familiar with the surface on Vacor boulders.

There are two surface characteristics (orange peel and wrinkles).

The orange peel on the surface is a direct reflection of the marble auger surface.

The wrinkles are from the underlying molten glass shifting and causing the thin cooled surface to fold.

Kind of like the folds you see on a Miller swirl or rams head marble.

I don't know if Steph's original question was directed at high magnification defects.

Sincerely,

John McCormick

"Shamrock Marbles"

Link to post
Share on other sites

I will agree there are at least two types of Orange Peel. Roller marks (very obvious on the Alox run done at jabo) and shrinking? glass marks which are very obvious on lots of large Vacors, Sorry John, but the more I look at them the less it appears rough rollers had anything to do with the marks. I wish these pictures were clearer but there are not the scratches inside the wrinkles one would expect to see if it was debris on the rollers causing these wrinkles. And these really are more like wrinkles than pressed in marks. I tried to show where you can see the rollers have actually flattened the tops of the wrinkles

1554117007848.gif

8608797.JPG

90226241177.gif

Link to post
Share on other sites

Galen:

Great photos!

I can see what you mean.

The wrinkling you point out that looks like your finger-tips pruning after being soaked in water for some time.

They are not round like a crater on the moon, but more grooved or kidney shaped.

Simply, they are dimples that have been distorted from the underlying "soft" glass shifting.

Once that top surface develops an impression from the augers and cools, there is nothing the rollers can do to completely smooth out the surface.

there are not the scratches inside the wrinkles one would expect to see if it was debris on the rollers causing these wrinkles.

I'm not talking about debris on the augers.

The augers are pitted from non-uniform oxidation.

Next time you're near a machine, take that scope/camera and record the surface.

Particularly the first three to four revolutions after the gob landing spot.

Now incidental debris/dirt falling onto the rollers can cause impressions.

Sometimes that debris hangs on.

We've seen it with bits of refractory or fire-brick.

But most frequently seen with bits of glass purposefully sprinkled on!

The scratches inside the wrinkles comment has me baffled.

Can you further explain this smoking gun theory?

Sincerely,

John McCormick

"Shamrock Marbles"

Link to post
Share on other sites

The dirt, rust, texture on the rollers is very rough at the microscopic level. They leave a multitude of scratches on the surface even when rollers appear super clean and smooth. (seen in the first pic I posted.) There do appear to be a few different patterns on the surface that different rollers can make but all the patterns are scratches. IItlooks like the inside of the wrinkles have few(er) scratches leading me to believe they are not made by mechanical force but something else like uneven cooling. Studying these surfaces has let me see how the so called "exotics" have the exact same surface patterns as CAC slags which give me even more assurance that they are genuine. Here is a pic of a new contemporary 5/8" marble. Sure easy to see the difference from hand and machine made at this level of magnification. I need to put a few of your mibs under the scope to see what their surface looks like!

post-87-0-94213900-1447629404_thumb.jpg

Link to post
Share on other sites

That just may be the process??, I think the wrinkles start forming in a fairly narrow time period when the glass starts cooling and the rollers have time to flatten the tops of many of the wrinkles before the marble gets hard. The wrinkle forming must be fairly fast and at a certain time or the wrinkles would be rolled flat or the tops not flattened??

Link to post
Share on other sites

Galen:

That just may be the process??, I think the wrinkles start forming in a fairly narrow time period when the glass starts cooling and the rollers have time to flatten the tops of many of the wrinkles before the marble gets hard. The wrinkle forming must be fairly fast and at a certain time or the wrinkles would be rolled flat or the tops not flattened??

Please don't take offense, but I'm going to let you develop your theory/explanation a little bit more.

MARBLE VALLEYS

Here is where I scratch my head...

Let's use COE 96 glass.

The thermal linear expansion is 9.6x10^-6/K (0.0000096/K).

The change in length = L1 x 0.0000096 x (K2 - K1)

Assuming the molten glass hits the rollers at 2200F (1478K) and becomes rigid (no longer pliable or mechanically mutable) at 1000F (811K)...

A 1-5/16" diameter marble (1.313") would change (1.313 x 0.0000096 x (811 - 1478)) = -0.0084".

For argument sake, let's consider that the glass matrix is homogeneous (same throughout).

I would presume that all the glass would shrink uniformly and not have zones or pockets of different COE glass.

Just having trouble...

Sincerely,
John McCormick
"Shamrock Marbles"
Link to post
Share on other sites

Way too technical for me. Sorry, it starts taking the fun out of it when I have to think too hard(LOL) I just compare it to what some kinds of paint look like when too thick and it dries too fast or too slow? The look is almost identical. Probably way different processes but the same results. Orange peel texture. I have also seen fused glass come out of a kiln that got an orange peel texture.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...