Mesh Attachment to Frame History

There are many instances of processes becoming outdated, only to flourish again years or even decades later. One of those processes is how the mesh is attached to the frame.

Stretch and Glue

When screenprinting was first used in 1852, the mesh was glued onto the wood frames of the time. Wood was inexpensive at the time, and nothing else that could serve the purpose well existed. However, as the tension decreased and off-contact was increased, the mesh would delaminate from the frame. The glues that existed at the time were susceptible to the solvents and chemicals used in the screenprint process and drying out over time and delamination.

Cord and Grove

Eventually, an enterprising (and unfortunately unnamed) screenmaker developed the cord and grove attachment method. The wood frame had a groove cut into the bottom side of the frame. A cord pushed the mesh into the track on two adjoining sides to hold it tightly. This was followed by pulling the mesh tightly across the frame from the two opposing sides and pushing the mesh into those groves—allowing for a tension level that was barely adequate and usually uneven. Still, this was better as the tension did not allow the cord to be pulled from the groove. The mesh could be removed from the frame by pulling the cord upward. This facilitated the retensioning of the mesh as it relaxed or was damaged.

However, as wood swells and contracts, eventually, the cord could loosen and slip from the groove. This created the need for a better and more permanent way to attach the mesh to the wood frame.

Upholstery Tacks

The following method employed upholstery tacks to hold the mesh to the frame. This method proved more beneficial than the stretch and glue or cord and groove methods and quickly became popular in screenmaking.

Staples

When we think of staples, the first thought is paper fasteners. The first known device to hold multiple pieces of paper was made in the 18th century in France for King Louis XV. But this was not a staple. The first true staple was in 1877 when Henry R. Heyl filed patent number 195,603 for the first machines to both insert and clinch a staple in one step, and he is considered the inventor of the modern stapler. Though in 1895, a revolutionary machine we would now recognize as a stapler was developed by E.H. Hotchkiss Company in Connecticut. It used a strip of staples wired together to solve the constant reloading dilemma. Still, these devices did not allow for stapling mesh to the wood.

It was not until 1934 when the staple gun was introduced and patented, that screenmakers began using staples over upholstery tacks. The speed of applying the mesh was sufficiently faster. There was a downside as the staples tended to cut through the mesh. At this point, they borrowed a trick from upholsters who used a strip of canvas above the fabric to prevent the cutting from occurring.

Back to Stretch and Glue

With the invention of synthetic adhesives and metal frames, there was a return to stretch and glue frames which flourished for years. Stretch and glue wood frames are still used in some segments of screenprinting, although mainly relegated to hobbyists.

The Decline of Wood Frames

While the synthetic glues were superior, they could not eliminate the problem of bowing under the mesh’s force and the wood’s deterioration. As the demand for wood grew and the old-growth trees diminished, younger trees were used, and the bowing of the weaker wood created extensive problems for screenprinters. Tension levels on wood frames decreased, and the maximum tension dropped to less than 28N/cm² at most. By the time the frames were shipped to a distributor and the end-user, the tension level was at a dismal 20N/cm² or worse.

Tension is just one reason the wood frame lost favor in the industry in the 1980s. Screenprinters could not ‘see’ tension, and thus it did not hold a particular significance to those who continued to use them. Only when the wood began to warp and the frame would no longer lay flat on the press bed, or the corners became loose, and the frame begin to fall apart did they admit that they had a problem and begin replacing them.

Wood frames begin to deteriorate as they are assembled, especially when the mesh is attached to them due to the force of tension. There can never be a return on investment with this type of frame. As the frame weakens and the mesh loosens, the user will find they are making two or more passes of the squeegee to make up for the inadequacies of the frame and thus spending twice as much time printing.

Aluminum and Steel Frames

In the commercial screenprinting segments, metal stretch and glue frames have replaced wood, especially those using stainless steel mesh. Surprising to some is that while aluminum and steel frames cost less to manufacture than wood, the selling price is based on the value of the superior attributes of metal frames. Metal frames quickly filled the warehouse shelves with higher margins for the distributor and the increased margins earned from replacing the mesh for their clients as they lost tension.

Owners attempted to cut costs for a while by replacing the mesh in-house. Still, as the cost of real estate increased, the cost of maintaining the equipment necessary to grind the glue from the frame and tension the mesh became absorbent, they began to move to retensionable frames, such as the draw-bar frame.

Retensionable Frames

By the mid-1980s, those who desired the highest quality had moved to retensionable frames, which use a locking mechanism to hold the mesh into place rather than an adhesive. Not only are the desired tensions attained, but the end-users can retension the mesh as needed. And the end-user saves the cost of shipping the frames back to their distributor as they can replace the mesh in-house within minutes.

With lean manufacturing and the desire to cut waste, screenprinters began switching to retensionable frames worldwide. Tensions of 50N/cm² or more are easily maintained, and off-contact distances have decreased to as little as 0.03125-inch (0.793mm), both of which relate to higher squeegee speeds with better shearing and lower dwell times. Who doesn’t want a higher production rate and more revenue?