Q. Are the Ball jars with the number 13 on bottom worth more money and, if so, why?
A. The ‘Urban Legend’ is that moonshiners used mason jars for their product, and, being superstitious, would break the 'unlucky' ones with 13 on the base. This made the jars rare.
In truth, moonshiners did in fact use mason jars as the preferred container for their product. They were a known capacity, were readily available and buying them did not raise suspicion.
Also, jars with 13 on the base are rarer than single digit numbers. But all the double-digit numbers are rare. The numbers designated the position that the mold occupied on the glassmaking machine, and there were usually 8 or 10 positions on the machine. The higher numbers were used when a mold was replaced. Dealers sell jars with 13 on the base at a higher price, but fruit jar collectors and the published price guides do not consider the number on the base to make any difference in value.
My opinion is that while moonshiners may have been superstitious, I can't imagine that the housewife would break jars just because they had 13 on the base, and housewives used more jars than moonshiners. I think that the urban legend was created by antique dealers who wanted to make more money off an otherwise common jar.
Q. I have found jars that say Ball only on the base, with nothing on the side of jar. Some will take a fruit jar lid, but others have a different size mouth. What are these?
A. The containers you are talking about are called packer jars, because they would be sold to another company who would then pack their product in it. They would put their paper label on the side. That's why the Ball name is on the base.
Ball always made packer jars in addition to their more famous fruit jar. The early ones had no identification. Sometime, possibly in the 1920's, the name Ball only was put on the base. By the 1930's, the name and a style number were on the base. Sometime after World War II, the style number was changed to include a hyphen. Later, plant codes were added.