The platen is most important part of the press as it ultimately affects the quality of the printed product. The purpose of this post is to point out the material choices available for platens and how these choices affect your printing, your quality and ultimately your very existence in business.
Without a smooth, flat platen, heat resistant platen you will not get quality printing. Yes, increasing the quality and gaining consistency in your printing should be your number one goal in achieving success. This will take you further than any amount of money spent on marketing, sales, advertising or a fancy logo and signage. It will take you closer to your goals than the old adage – Location! Location! Location!
Achieving quality relates to the best way to increase the return on your investment and become more successful! If you were still in high school and this was your first experience with screenprinting a lesser concept might suffice, but for most of us this is our livelihood. The livelihood of your family, as well as your employees and their families as well. With all this at stake, doesn’t it make sense to invest in equipment and components that will allow you to perform to your optimum?
The platen is also referred to in the industry as a pallet, shirtboard, print bed, printing table and any other number of terms. The terms are geographical and also relate to the substrates being printed, i.e. graphic printers generally use the term printing bed, while textile printers have used the term shirtboard at times. The term platen seems to be the most widely used term, however.
Platens can be made in a wide diversity of sizes, shapes and material dependent upon the production needs of the individual shop.
Characteristics of a Platen
– The platen must be flat
– Must be rigid and flex resistant
– Surface must be free of defects
– If a flash is used, the material must be able to withstand the heat
Composition Wood Platens
A great number of inexpensive presses are made with particle wood or medium density fiberboard (MDF) platens. These are actually sink cutouts from countertops purchased in bulk from a cabinet manufacturer who otherwise would discard the leftovers. This keeps the price of the press to a minimum on the original purchase. But it sends a message to some that it is okay to use these cheap platens to print on forever. This is not the case. Just like the cheap tires that come on all new cars that wear out quickly and must be replaced, you should consider replacing the platens after you get past the beginner stage. Think about it like a race car driver, they would not dare use the same tires on their race car as they would use on their car that they drove around the neighborhood. Of course not, the race track presents a completely different need. And just like that race car driver if you want to perform at your optimum, producing the highest quality possible, with the greatest amount of ease, you will do well to consider switching to the very best equipment and especially platens possible.
Composition wood platens will warp, bow and cup and thus are poor choice. The heat of a flash unit will cause more damage to the composition platens. The moisture and resultant steam will quicken this affect. As the wood ages, it has a tendency to cup or bow thus creating an uneven surface that will make printing difficult.
When the wood cups, i.e. becomes lower in the middle and higher on the sides the subsequent ink deposit will be less on the outside edges and thicker in the middle of the print. If the wood bows, you will get the opposite affect. The ink deposit will not be able to cured evenly and may degrade on the printed shirt. Also detail will be lost from the uneven surface. You could continue to sand the wood as it degrades or you could begin with aluminum for the press surface.
Formica or Melamine Covered Platen
Some printing press manufacturers laminate a sheet of Formica or Melamine to the medium density fiberboard platen section of the press. This laminate produces a smoother surface that can be easily cleaned.
However, these platens have their downside as the laminate does little to keep the wood platens from cupping and bowing. In fact, the laminate itself, being a form of plastic is susceptible to degradation as the surface will burn from the flash unit. This burn will cause a blistering, which must be sanded down before the platen can be used again. Also, as the plastic surface is glued to the wood with a non-heat resistant glue they will delaminate as heat builds up from the flash unit. Remember, these were only meant to be suffice as countertops in a home kitchen, and never to withstand the rigors of printing, heat, and abuse we throw at our platens.
Aluminum platens are the most widely used platens by printers as their durability, longevity, and printing quality, offer a good return on investment. Aluminum platens warp less then wood. And solid aluminum can withstand the heat of a flash unit better than other materials. They can also be refinished as necessary should they become marred.
There are many different grades of aluminum. The differences between the grades is immense and the use of inexpensive grades should be avoided. Only the very best materials should be considered. If purchasing aluminum platens one should pay particular attention to the most durable grades, which will be very flat, on plane and able to withstand the strains imparted by the process.
However, there are downsides to aluminum platens. the solid aluminum platens retain heat and while flashing time may be decreased it will vary during the press run as the platens heat up and retain additional heat. An additional factor is the weight of aluminum as compared to MDF clad Melamine.
Aluminum platens can be covered with a 1/8-inch, heat-resistant rubber covering. This offers an optimum printing surface. The use of rubber coverings will be explained further down in this text.
If you’d like to use an aluminum platen I suggest that you contact Action Engineering at Action Engineering-Home for manufacture. They have over 30 years of experience and use only the highest grades of aluminum to manufacture platens for any need. They have stock replacement platens for all popular manual and automatic presses. They also make specialty platens for printing across the shoulder or all over, sock platens, leg platens and well… you name it. Check them out.
Aluminum Honeycomb Platens
Aluminum honeycomb platens have been a huge advancement for the screenprinting industry. This specially designed material was originally developed for the aviation industry. The material is basically a three-layer sandwich in which a honeycombed core is laminated top and bottom with thin sheets of aluminum. It is the honeycomb core that presents the greatest advantage to these platens.
The resulting sandwich results in an exceptionally warp resistant, rigid, and lightweight material. The weight of a 1/2-inch aluminum honeycomb platen is 75-percent less than a 1/4-inch solid aluminum platen.
There are different types of honeycomb cores produced. A larger cell size will reduce the weight and dissipate the heat more rapidly, however will reduce the available amount of surface for gluing the aluminum laminates. This reduces their effectiveness and durability. Therefore, the cell size is an important specification in ordering aluminum honeycomb platens.
Other than weight, the aluminum honeycomb platens exhibit another advantages. They will stay flatter than any other type of platen thus offer a much improved printing surface.
However, aluminum honeycomb platens have their limitations, as well. All aluminum platens must be a minimum thickness of 3/8-inch in order to have the necessary stability and to be able to resist the heat of the flash unit. The very best aluminum honeycomb platens are at least 1/2-inch and 3/4-inch material would be a better choice. On another note, the aluminum honeycomb platens have a thinner surface and will be subject to surface denting and must be handled with great care.
Aluminum honeycomb platens are more commonly used for large format print, i.e. generally larger than 20-inch x 24-inch platen sizes. While it is true that for the larger platen sizes this product is an exception product, because of its attributes, it can be considered a viable product for all platen sizes.
The biggest disadvantage to aluminum honeycomb platens is their inability to hold up well to the heat of flashing. The material takes longer to cool down than solid aluminum. Because the aluminum surfaces are laminated to the core using heat degradable epoxy, excessive heat can cause delamination of the sandwich. The addition of rubber can result in a greater amount of heat retention and thus the susceptibility of delamination.
Rubber Covered Platens
The best platens on the market will be covered with rubber. The heat-resistant, 1/8-inch thick, rubber covering can be applied to any type of platen material.
The better rubber platen coverings will be designed to withstand very high flash temperatures, but can be destroyed if allowed to sit under the flash unit.
Although rubber covering is a cost factor and it will require replacement from time to time, the advantages to this product are many. The rubber surfaces acts to reduce and may completely eliminate the slight surface irregularities in the surface of the platen. It also accepts and helps with slight differences in the plane of the platen. Another great reason for rubber-covered platens is that provide an improved ink deposit onto the surface of the substrate. On dark garments, you will find that the subsequent print will be more opaque and even.
Because the platen will retain heat, the addition of the rubber covering increases the thermal properties by holding the heat much longer and more evenly than a platen without rubber. This means that because the platens stay warmer longer your flash times will be reduced. The disadvantage will be the holding ability of the adhesive will be lessened.
The use of waterbased adhesives is widespread in the textile industry. The cost savings is the biggest reason, as it is possible to print over 1,200 shirts before the adhesive must be replaced on the platen. This number is reduced when printing with textile items with an extreme amount of lint or when flashing, but still one will see an extreme cost savings over using spray adhesive.
Speaking of spray adhesive, its use has declined because of the overspray, which saturates the shop and the subsequent lint that adheres to every surface, imposing a fire risk. The use of spray adhesives also pose a health risk to anyone in the general area of these products.
This product is a fairly recent innovation in the screenprinting industry. Platen tape is essentially a thin, wide masking tape that is available in various widths that match up to the common sizes of platens. It is available up to 24-inches in 25-, 50-, and 100-foot rolls.
The tape is applied to the platen in order to save the time and expense of cleaning. Waterbased adhesives are applied to the tape and as lint builds up, the platen can be easily cleaned with a moistened open-celled sponge. The dampness can be quickly dissipated with the flash unit and printing can be continued.
Hope this helps. I’d certainly like to hear comments on this post.