I was recently presenting a 3-hour entry level screen printing seminar at a trade show. Before beginning, attendees from two separate companies talked to me saying they had many years of experience but were looking for tips and tricks to improve their operations. One company stayed and one left based on my response.
When I began talking about pinhole issues, the company that stayed sat smiling and nodding to one another knowingly. Surprisingly, the second company spoke to me afterwards and said, “We’re just really looking to find a way to rid ourselves of pinholes.” It seems the two companies who showed up with many years in the screen printing trenches were both having the exact same problem in their shops.
My takeaway from this was that every company, small or large, newbie or veteran, can learn something to improve their business. Or, in this case, relearn something that they may have inadvertently gotten away from doing in their day-to-day operations.
My conversation in the seminar as well as my conversation afterwards began with these companies explaining all the reasons they were experiencing pinholes. They listed one cause after another, but apparently whatever they tried to do to correct these self-diagnosed issues, the pinholes persisted.
I let them talk, and let them theorize, and let them explain to me what they needed to do to fix the problem. And then I simply responded, “I don’t know how you run your business or the processes you follow in your prepress departments, but I do know why you’re struggling with pinholes.”
Pinholes are those tiny dots of color that appear on your garments as you print, multiplying as you go along until the bottom of your screen can become a mess and tangle of tape, attempting to patch and cover these small holes. The longer your production run, the more pinholes tend to open up in your screen as you print.
Degreasing of screens is the singular key factor is dealing with pinholes in your screens. It is such a simple solution that many screen printers assume it is either 1) not important, or 2) can’t be as critical as I tend to make it sound.
New as well as used screens need to be properly and suitably degreased before coating with emulsion… every time. There are folks in the industry who will tell you the degreasing step is not always necessary. This advice is 100% wrong.
Contaminants on your screen before coating with emulsion will absolutely cause pinholes. Period.
New screens come to you with machine oil, oil from the hands of everyone who has touched them, dust, lint and other contaminants. All can impact adhesion of emulsion to the screen mesh and cause pinholes on the press. Oils on the screen will not mix with your water based emulsion.
Used, reclaimed screens also have oil, chemicals, dust, lint and contaminants from your shop, and must be properly degreased as well. The degreasing step is an absolute necessity each time a screen goes through the reclaiming/coating cycle.
Most screen printing suppliers carry a professional degreaser and this product is fairly inexpensive. If you are looking to save nickels and dimes in your shop, you can buy Simple Green at many hardware stores. Simple Green is a pure detergent that will work perfectly fine as a degreaser, but some people are sensitive to the slight odor.
In my classes and seminars I often get the question, “Can I just use my grease-fighting dish soap from the kitchen?” In a word, the answer is, “No.” Most if not all of these products have hand softeners, which are oils that will defeat the purpose of your degreasing step.
The answer to pinhole issues in your shop is almost always in the degreasing step. Proper degreasing every single time you begin the process of coating your screens with emulsion will virtually rid your production floor completely of these tiny yet annoying little pinholes that ruin shirts and stagnate production.