Marble Pictures


Manufacturers Information Pages

Marble Articles
Marble Shows
Buy/Sell Marbles

Marble Photography
Marble Games


Hey, JABO, Your Butt Crack is Showing!
By Steve Sturtz

A huge thank you goes out to David McCullough who has granted permission, for the first time, for the following secrets to be revealed. This article is a present from David and me as a tribute to our friendship with Edna “Spikey” Eaton, president of the Texas Marble Club.

We wish you, the management team of the Texas Marble Club, great success and a long and prosperous future. We know Edna will provide great leadership.

The JABO factory is a Disneyland for adults. If you are a marble enthusiast and you visit it once, you will always want to go back. David loves watching visitors trying to figure out the machines and how he does certain things. He will tease the visitor with little snippets of information and then, when the person gets one piece of the puzzle, he will tell him that he, himself, had never thought of that and that you, an ingénue, just taught him something. That is only one of the many reasons he has earned his nickname – Dennis the Menace.

In my third book, “2008 JABO Classics: The Experimentals”, I talked about the standards of excellence David set last year in marble-making in terms of oxblood, aventurine, mica, number of colors per marble and complexity of pattern. I go on to tell this story:

“‘Right now, these patterns I have seen, I think I’ve figured out what it is all about. I think a few more runs will tell me more,’ David mused. ‘I do believe that we can get that complete pattern all the way around the marble.’

The standards of the intricacy, action, and patterns of marbles have been changed forever. Many of us can think of lots of very active swirl marbles from other makers such as the Peltier Miller Swirls. But as the year 2008 went on, the patterns of the Experimental marbles became more intricate.

When I arrived in Reno, a couple of days before the Last Dance Run (December 16th, 2008), David McCullough asked me if I noticed any adjustments in the machine. I looked, but I could not see it even though I thought I knew what I was looking for. I told him I could not see the change. He just winked and gave me that Dennis the Menace, dimpled smile as he looked over his glasses. He did not show me.

When the Tribute to Friendship Run (March 5th, 2009) came around, I made a bee line to the machine which was not under the tank yet. I looked and looked – nothing. Dejected, I went into the trailer, planning on using my best, creative, begging skills. I asked, I begged. Then David smiled and, with a laugh, said, ‘Go on out. I told Richard to show you.’

Richard and Ronnie stood and chuckled as I looked – nothing again. Then they gave me a small hint – nothing. Then they told and showed me with great pride. I started to laugh and the harder I laughed, the harder they laughed.

He had adjusted those machines yet again to strive for another first. He is now able to create an intricate pattern where not only do the stripes get thinner but they go all over the marble. They go all the way around the marble to all four points of the compass. Once he explained the adjustment to me, it was so simple. Here is a master glass maker, who, although he knows his machines and craft so well, had taken a long journey to discover this technique. When he figured it out, complexity became simplicity.”
(excerpt from 2008 JABO Classics: The Experimentals. Sturtz, Steve.

As with most great inventions or ideas, they have their beginnings in a happenstance. A few years ago, the floor at JABO needed repairs. The feet of the marble machine were in two holes and hence the hot stream of glass had further to drop before being sheared off. The ensuing marbles contained a more intricate pattern.

When the floor was repaired, the marbles returned to the typical JABO pattern and David continued to make marbles. As mentioned in my second book, “David’s JABO Renaissance”, it wasn’t until the fall of 2007 that David began to expand his experimentation with marbles in preparation for the Experimental runs of 2008. He thought about changing the pattern of his marbles as well as adding aventurine, more colors, oxblood and mica. Every experiment in the last eighteen months has a precedent in the past that McCullough has already tried.

There are those who would tell you that making marbles with a machine is very easy and that what you throw in the back comes out the front. The real marble-making doesn’t happen in the tank when the glass is molten and red hot and it certainly doesn’t happen when it comes down the rollers. By then, it’s long over. The real secret to marble-making (and it takes hours and hours and hours) is the planning that goes on for weeks before the run. David McCullough spends an awful lot of time talking to the investors about where they could go and how they could get there. We have already been working on the 2009 Fall Runs for two months and will spend another two months phoning, talking and questioning before they occur.

Let’s start by telling you that the very complex patterns are caused by having as long a
length as possible from the bottom of the tank where the glass comes out red hot to the little cup where the glass builds up in cow patty-like shapes. Here, the shears cut it off and it becomes a cylinder as it rushes for the rollers. The longer the distance from the bottom of the tank to the shears, the more the glass stream gets thinner because it goes farther. It is akin to pulling taffy or soft-serve ice cream coming down from the nozzle. Because it’s thinner, it piles up on itself and the colors are then distributed in a more complex fashion all the way around and through the marble. Therefore by elongating the distance from the bottom of the tank to the cutter, more complex patterns are created. For the first time, there are patterns that really go all the way around the marble. This discovery was revolutionary.

David began experimenting with complex patterns on the first Tribute Run in September and continued to experiment with each consecutive run. By the time we got to the Tributes’ Last Dance Run in December of 2008, he had achieved the complexity of pattern by lowering the machine so the distance from the tank to the cutters was longer at the rear of the machine. However, he hadn’t lowered the front end of the rollers, where the marbles roll off. This resulted in many marbles with cold roll marks. So when we got to the next run which was in 2009, the JABO Tribute to Friendship, David had figured out that the secret was to also lower the front so that the front and back were at the same height. When he did that, it cured the roll marks. So, the run where he was most completely successful for the first time was the JABO Tribute to Friendship Run and he, as well as the Tributes, were very pleased.

 Complex Jabo Pattern

Figure 1 – elongated tube that will form a complex pattern on a marble

Many runs since then have had the benefit of this experience. It tickles me to no end how many people think how easy it is to make marbles and yet David’s search for this complete pattern has taken him thirty years. I have teased David many times about the fact that it has taken him such a modest length of time to become an instant overnight success. Here is a master glass maker, who although he knows his machines and craft so well, had been on a long journey of discovery before he was able to work it out. When he was successful, complexity became simplicity. When you have found simplicity, you have found your best work. David has certainly done that with all of the Experimentals of 2008 and then, with the Classics he has made in 2009, using all of the things he had learned.

The other side of that coin - the perfect negative correlation are the butt cracks. The butt crack is created using the exact opposite of the very complex patterns.

Butt cracks are formed when the machine is much higher and the distance from the tank to the cutter is much shorter. The flow of glass, therefore, is very thick and so it fills up the little cup quickly before the cutters come along. As a result, it is thick enough so that on many marbles, it only folds over on itself once forming the butt crack. Then when it is cut and it goes down the shoot, it hits the rollers, jiggles a little and it gives it that final little twist at the end of the butt crack. Often I look at these marbles and I think of the yellow ribbons or the pink ribbons people wear on their lapels as tributes to cancer victims or to the military.

Tube that creates butt cracks
Figure 2 – tube formed from the shortest distance from the tank to the cutter.

It is fascinating that David didn’t understand or didn’t figure out the butt crack until after he figured out the complex pattern. It is amazing that as hard he has


Butt crack fold

Figure 3 – tube of hot glass folded over to create a butt crack

searched; as often he has looked;
and as often as he thought daily for thirty years, it was elusive! But, suddenly, bang, there it was. After the complex pattern was figured out and tried on a few more runs, eureka. David realized that he knew the answer to the question of the butt crack.

What you learn by standing at the hot end of the machines and talking for hours to the guys who have worked there for ten to twenty years and David for thirty, is that the minute adjustments on these machines can make any sort of change in the architecture of the marble. The number of combinations of adjustments is pretty well broader than most folks realize. When people see the V’s or a particular patch or a particular pattern on a particular machine, they say, “Oh that is made by (fill in name of a company yourself) on the thus and so machine (fill in the name of a machine yourself) and they just assume it was made by that machine. Those people are collectors not marble makers. You can do a lot with any particular machine by making an adjustment.

Another example of this is the marble from the Tribute to Friendship Run called Griff. It is a double seam that almost looks like a patch and ribbon from Marble King and it isn’t. It is singularly the result of machine adjustment. It takes a lot of years of experience to know how to make these very small adjustments. Often we have seen those adjustments while standing in the factory and many times they were made for the first time while we stood there. We didn’t understand what we had seen. Often, even while we were standing right there, we didn’t see it done. We think now that anytime we choose, we can either have a complex pattern; we can have double seams or we can have a butt crack. Would you like David to make a Vitro “V”? Or, should he make a more complex Champion Old-Fashioned? Maybe some wire pulls are in the future?

I am very pleased and complimented and I hope the members of the Texas marble club are pleased and complimented that David has given me permission for the first time to tell these two secrets publically in this newsletter about the complex patterns and about the butt cracks. It is a tribute to the marble collecting folks in Texas and to the relationship David has with Edna and Weldon Eaton.

© Steve Sturtz July 2009
JABO: A Classic. Sturtz, Steve; Johnson, Michael.
David’s JABO Renaissance. Sturtz, Steve; Johnson, Michael.
2008 JABO Classics: The Experimentals. Sturtz, Steve.


Home    E-Mail    Marble Pictures    Manufacturer Information    Marble Articles
Marble Shows    Marble Photography    Marble Games    Marble Links 
Buy/Sell Marbles