Union Special is the last sewing machine factory in operation in the United States and has been in operation since since 1881. The machines they are known for are not primarily textile manufacturing machines but bag closing machines. If you've ever seen a paper bag or sack of flour or coffee that's closed with a line of stitches, that is what most Union Special machines are designed to do. Even today, bag closing remains the mainstay of Union Special's business.
The Union Special 43200G was invented in 1939 and was in production until 1989. Throughout that time the machines was the industry standard tool for chainstitch hemming of jeans and other garments such as overalls. The quality of the chainstitch that the 43200G has never been improved upon, which is why so many of the surviving 43200G machines are still in operation at quality denim workshops around the world.
The original parts manual (copyright 1938) and instruction manual are still available online. The instructions speak to the workhorse nature of the machine, with a command to the user to "Sew... at top speed. Operate machine continuously at 4500 R.P.M. STEP ON IT!". This is not a tool for the amateur or the faint of heart.
Chainstitches are essential in a pair of jeans. A chainstitch is made with two threads (a needle thread and a looper thread) wrapped around one another repeatedly in a chain. This is different to a lock stitch, which involves two threads (a needle thread and a bobbin thread) interlaced together.
A chainstitch has slightly less tension and more "spring" in each stitch than a lockstitch does, but the chainstitch also consumes more thread to produce and is overall a stronger seam. The extra flexibility means that seams that are secured with a chainstitch can move over time, build up in looser areas and pucker. Wear builds up in the puckered areas more than it would in seams where a lockstitch has secured the fabric more stiffly and evenly.
But why is the 43200G specifically so special?
Firstly, the 43200G has a static presser foot and two feed dogs, unlike modern machines with walking feet or other adjustments. This means that as you move layers of fabric through the machine, the top and bottom layers of fabric move at different speeds. This slightly offsets the layers of fabric at the hem of your jeans. Over time, this helps the denim to fade with the "roping" effect.
Secondly, the needle on a 43200G enters the fabric at an angle instead of vertically straight down. This causes the roping effect to take on a more three dimensional, diagonal appearance. Other machines create a less bumpy, two dimensional wear pattern, in line with the cloth instead of diagonal.
Today, many manufacturers do not use a 43200G machine for hemming. Most of the machines that Union Special made have long since gone out of service or been cannibalized for parts to keep the other existing machines in operation.
All Atlantic Standard jeans come with Union Special 43200G chainstitched hems. If you own a pair of jeans from another manufacturer that have not been hemmed with a 43200G and would like to have them re-hemmed (or if they are too long and you want them shortened) we can hem your jeans with our machine.