By Steve Conde
I have heard it a thousand times – should the temperature on my heat press fluctuate when I am pressing something?
This is both easy and difficult to answer. The simple answer is “yes”. When you close your heat press, you will see the temperature readout drop. This is because the item you are pressing is absorbing the heat from the heat platen and it takes times for the platen to recover so you see the temperature go down, perhaps 50 degrees before it states coming back up.
The amount of drop depends on what you are pressing. Something that has a lot of mass like a UNISUB plaque will absorb a lot of heat while a garment will absorb very little, and pressing several items at the same time will absorb more heat than pressing just one. So “yes”, you can expect your temperature to drop from 10 to 50 degrees or so when you close your press.
Now comes the hard part: How long does it take for your heat press to recover the lost heat? In a quality heat press, that happens very quickly and by the time you remove your product the press has fully recovered and is ready to go again.
The problem is with heat presses that either don’t recover quickly or just plan lie and I’ve seen both. What makes a heat press “lie” is a lousy temperature gauge. Not all gauges respond quickly to what is happening on the face of the platen and may take several minutes before reporting a change in temperature. This was pretty much eliminated when electronic thermal devices replaced the older gauges but even an electronic readout can be poorly calibrated and that eliminates any hope of knowing what is really going on. See the blog about checking accuracy.
But what concerns me more than a cheap or inaccurate readout, is a cheap heat press. A heat press is really a pretty simple machine. They all look pretty much alike and have the same basic parts. The most important of these is the heat platen (the thingy that heats up). All heat presses heat up, some faster than others and that’s our first clue to a problem. We all want our presses to heat up to 400 in a matter of minutes and a few presses actually do but are we trading off something to get that? YES! Here’s the deal: A press that absorbs heat quickly, also gives it up quickly and that we don’t want. We want a press that is stingy about giving up its heat and is quick about recovering any heat it does give up. This can be accomplished by simply increasing the thickness of the heating platen.
George Knight presses, for example, have a ¾” heating platen. This is at least half again as thick as some presses on the market. Having a thicker platen means it will fluctuate less and recover quicker than a press with a ½” platen.
Here’s where the problem usually shows up in real life: Press a series of heavy items one right after another. For example: Press a ceramic tile or UNISUB plaque and as soon as it comes out, put in the next. After doing this three or four times, you could begin to see a drop in quality from one piece to another. The reason? The press isn’t recovering the heat it has lost on the previous product.
You could say the solution is just to wait for the press to recover before pressing the next item and you would be correct BUT, you shouldn’t have to do that. A good press will recover quickly enough that you shouldn’t have to wait for it or wonder when it might be ready for the next product.
Ever find that everyone else is making a product in 6 minutes and it takes you 8? That’s because your press is giving up too much heat and can’t recover. Find yourself trying to figure out pressing times for multiple products? Say, the first sheet of name badges takes 60 seconds but the second takes 90 seconds to achieve the same quality? That’s your sign: your press is giving up too much heat – probably because the platen is thin.
All presses may look pretty much alike but believe me, they aren’t. Learn what to look for in buying a press. We will be talking more about this subject in future blogs but number one on the list is the thickness of the heat platen. Don’t be fooled by fast talk, know the facts.
