Heat Pressing 101

Let’s talk about heat presses as they are a very popular and useful tool for screen printers.  Whether you are decorating apparel with heat press material, ink transfers, or sublimation, the style and quality of heat press you choose is an important decision.  Today we want to educate you about heat pressing and the problems you may experience so you can make good decisions regarding any future purchases of equipment or decoration materials.

Where to start…how about the basics.  When decorating apparel with a heat press, it is very important to apply heat press material, sublimation, and ink transfers at the correct time, temperature, and pressure.  It is also important to peel when you are supposed to peel.  As you may or may not know, each of these decoration methods may require a hot, warm, or cold peel.  Sometimes it can be any of the three.  Regardless, following these instructions is critical to your successes.  Following instructions is also easy.  A big however though as the newest high tech materials and ink transfers are made for low temperature applications.  This is where we have some concerns.

You see, low temperature ink transfers may be printed on certain hot peel papers or any cold peel papers.  Often, if you peel an ink transfer hot when it is a cold peel paper, it won’t peel.  If you peel a hot peel paper when it is cold, it will also not peel.  If you wonder why we am boring you with peel details it is because the heat press has more to do with this than many of our customers realize.  

Here in Louisville, we use a clam press.  It is pretty nifty as it opens itself when the timer is complete.  The decoration is immediately right there in front of us and we can hot peel the paper or plastic backing right then and there.  It is quick and efficient.  Some presses are swing away models where the heating element is raised up and then needs to be turned away from the platen.  At this point you can peel right away.  Oh wait, you have a paper or coated cover sheet.  You have to peel that away to then peel away the backing.  Other heat presses have a slide-out platen that acts like a drawer in a lot of ways.  This offers a similar slow process to getting to the backing to peel it off.  

Again, there is a reason we are getting to the point of how long it takes to peel the backing off.  These new materials and transfers have a low temperature application.  They are typically hot peel.  What if the material isn’t hot any longer?  That is what many people are running into.  Their hot peel application is more of a warm peel and this may not work well.  If you choose a swing away or another modern style of press where you are unable to peel the backing quickly after the press is finished, you may get poor results.  Edges may lift.  For this reason we recommend a clam press or simply operating these other styles of presses very quickly to be safe from any problems.

A lot of other things can go wrong when heat pressing.  A common problem is too much or too little pressure.  Air operated heat presses give you the dial for psi which tells you exactly what the pressure is.  Some clam presses will display a 0-9 once it is closed which gives you an idea of your overall pressure.  1-3 is light pressure.  4-6 is medium pressure.  7-9 is high pressure.  When these go blank, that actually means you are very heavy pressure and probably need to tone it down.

Even pressure is just as important as overall pressure.  If a collar or sleeve seems are on the platen when you heat press, much of the pressure is being applied to those instead of the decoration.  This causes problems.  In these cases, you really need a heat press pillow.  This handy tool is a foam filled, teflon covered cushion that you can place inside your shirt or simply tape to the platen.  This will allow collars, zippers, sleeves, pockets, and other raised portions of the apparel to sink in and the decoration will get a nice, even press.  It is a must-have item.

Another concern is heat.  Sure, it is easy to set the digital thermometer to the temperature you would like.  The problem is that these are often not accurate.  Test with an infrared thermometer/gun as we have run across far too many heat presses with problems lately.  Perhaps the heat is correct in the middle but the edges are far too cool.  Perhaps none of the heat matches the thermostat.  Either way, you won’t know unless you test and we can assure you this is far more common than you want to believe.

The style and brand of heat press equipment you choose is up to you.  We really just wanted you aware of what you are getting into and what type of problems you may experience.  As with everything here at One Stroke Inks, we demand low temperature applications.  The fabric begs for it.  Your customers will appreciate it when their goods don’t have scorching, discoloring, and the glossy square which occurs so easily on 100% polyester.

Speaking of the glossy square on 100% polyester, we see many of you always use a cover sheet.  If it is a Teflon cover sheet, you just made this glossy square far more likely.  The same goes to any of you who allow the heat press element to touch the polyester directly.  Try Kraft paper or some sort of paper cover sheet instead.  This will minimize any damage the heat press can cause polyester at higher temperatures.  Of course, the low temperature applications will minimize this dramatically.

Good luck with your heat press endeavors.  As always, I am here if you have questions.