Sunday, January 23, 2011

Hi-Density Printing and the Emulsion that makes it possible

Hi-Density printing, or thick as a brick ink has always been problematic to me because of the screen making process required to have a thick enough stencil to on the screen that would allow a super thick build-up of ink when printing. I stopped at one booth at the ISS tradeshow that had a good strong hi-density screen as an example, can't remember the name of the company right now, but I was impressed with the crisp edges and durable feeling of the emulsion was. I plan to purchase a gallon of the stuff and give it a try, oh, but the good thing was that my previous experiments with the hi-density emulsion failed as I had to coat the screens many times to try and build up the thickness of the stencil. The process for this emulsion was explained as not having to dry in between coats. The way I tried high density emulsions in the past was by drying in between thick coats and it just got sloppy, messy and too difficult to expose the thickly coated screen.

Still more information about t-shirt printing and now laser versus dye sublimation

Always the last on board, I am not surprised that my devotion to laser printing is finally in question. I stalked the ISS Imprinted Sportswear t-shirt printing tradeshow in Long Beach for the Magic Touch transfer paper booth. Ideally this rather expensive paper would allow me to make multi-color t-shirt designs on dark garments, 100% cotton t-shirts, and eliminate the need for detailed trimming and weeding of the print design. This is a transfer technique, which I am also reluctant to endorse, but there are situations when transfers are appropriate, and I had a quest. The quest was strong enough that I got up before 10a.m. and got a Wellness Smoothie before driving for the last day of the show to find the Holy Grail of transfer technology.

I could not find the Magic Touch transfer demonstration at the show, so it must not exist, but I did have several conversations regarding dye sublimation and I now have a better understanding of the process. I have been reluctant to use dye sublimation because when it is used on t-shirts it requires the use of 50/50 cotton-poly t-shirts, or materials that are coated with a special chemical to capture the dye in the sublimation. As I understand it now the ink is printed on paper and then applied with heat to a garment or coated object. The heat then gasses at a high temperature in a heat press and saturates into the coating / polyester and resolidifies it's structure upon cooling.

The most interesting part of this equation is the coating, which has been described as resin of sorts, which simply means a poly resin. Hmmmm. Therefore the dye sublimation inks in gas form bond with polyester, which allows these inks to bond to the many types of plastic items that are used with the dye sublimation process. The claim is that the solidified dye sublimation inks are durable, like a polyester resin. I have not confirmed if these inks have any natural uv resistence or if they require additional coatings, like polyester resin products, to product them from degradation due to us exposure.

Laser prints are typically done with pigments ground finely to be used in toner cartridges and are printed with the printer by an evenly distributed electrostatic charge the bonds the colors to the paper until they are fused by heat. The pigments themselves have a natural resistence to uv as they are particles and the transfer papers seem to be carriers with the pigments embeded in a thin gelatin coating. I have always thought the dry, non-gassing process, was superior to the gassing dye sublimation process. However, if the gasses solidify into a resin form, like the coated material that they are bonding to, then they may structurally superior, minus the uv protection to the laser prints. The laser printed pigments are held together with the gelatin or coated material and therefore once that gelatin breaksdown the image is vulnerable.

For basic transfers and t-shirts or indoor items most of the durability questions are not relevant, but when you get into imitating fired items like ceramic cups and exterior tiles the durability is relevant. Also the gassing of the die sublimation is similar to the concept of the photo-fresco process that I have been working with, only it is the process through polyester resins versus the gypsum based materials that I have been working with. This does explain why some of the results I get when combining materials work better when I have used polyester resins and epoxy as the base material and ending up with the dye sublimation might be a natural progression. I always end up in the areas that I have tried to avoid the most, so this is no different.

Saturday, January 22, 2011

No Sleep Til' LONG BEACH - T-shirt Printing Tradeshow

I am always overwhelmed by how much information I can find at tradeshows and the Imprinted Sportswear tradeshow has not been a let down. First off I must warn you, I don't care that much about the latest trendy cut of t-shirts, there is always something there, but in the end my customers stay within a range of available goods and when they ask for it I get it. So I can find anything and I simply add a bunch of new companies product catalogs to my product line, but not very much of it performs over the long run. However, technical details with "experts" is my way of entertaining myself and finding out how little I have been doing to expand my t-shirt printing universe.

I focused on mesh adhesion and emulsions with my questioning of the Ulano and Sefert and IT sales people. I have found out that mesh is pourous, which means it will absorb chemicals that it is submerged, or embedded in, such as photosensitive emulsions for screen printing. I also found out that there is a clear, although not optically clear, emulsion and it may be possible to add pigment (liquid) to the emulsion in a variety of colors.

My other interesting exchanges were about discharge inks and Wilflex has a discharge ink that does not emit an odor or sulfur smell and does not require the final garment to be washed before it is sold. This ink has been popular in Europe, but is just being released in the United States and I'm all in. I've done some discharge through contractors, but have avoided using it directly as the smell and toxicity of the garments remains a problem if the shirts aren't washed before they are sold. Next step is to make samples of some new designs.