For years, commercial printers were busy and presses continually full with both small and large jobs as businesses counted on paper to advertise and promote their products, services, and causes.
Now, as organizations advertise themselves and sell their products and services directly over the Internet, as digital short runs have increased in popularity, and as environmentalists promote reducing paper consumption, the demand for commercial printing has abated.
Today, business savvy commercial printers are looking for opportunities to print on non-traditional (i.e.: non-paper) substrates such as fabrics. A key element of this strategy lies with a new generation of commercially available heat transfer papers that allow printing of simple to complex images on fabrics including soft signs, flags, canvas, denim, and t-shirts. This ability gives printers the opportunity to use their existing equipment, materials, and finishing capabilities with current and new customers to help grow their business.
Heat Transfer Papers 101
High quality heat transfer papers have been around since the mid 1990s, so forget about the crackling and peeling “iron-on” transfers of years ago. The first thermal and laser products were introduced in the mid 1980s, followed by inkjet products in the late 1980s, and the first dark transfers in the mid 1990s. Self-weeding laser heat transfer papers have been around since 2005.
Today, heat transfer papers are available for a variety of applications, from desktop digital to high-volume offset printing. Some of today’s heat transfer papers have better environmental and product safety advantages than others, so printers looking to adhere to higher green standards should look for heat transfer papers that do not contain the following harmful ingredients:
- PVC (Polyvinyl Chloride)
- PFOs (Perfluorooctane sulfonic acid)
- BPA (Bisphenol A)
Offset printing using heat transfer papers provides an economical, fast, and efficient way to produce heat transfers for decorating t-shirts, sweat shirts, canvas bags, canvas notebooks, and other fabrics. Printers can sell shirts or items with printed images to produce revenue, or printed images can be supplied to the consumer for application by hand iron. In addition to line art, photographs and photo-quality images may be applied.
When selecting heat transfer papers for offset printing, it’s important to use different papers for light and dark fabrics. Heat transfer papers for dark fabrics should prevent the dark fabric dyes from discoloring the art or graphics. Since it is often not known what color garment they will be applied to, the products for dark fabrics can be used on both and solve the issue of which one to use. Both types of papers should:
- Eliminate offset ink migration
- Prevent ink bleed when wet
- Withstand many wash and dry cycles with good color retention and no bursts or cracks
- Be applied by heat press or hand iron
Tips for Production
While today’s heat transfer papers are easy to print, pre-testing of all procedures prior to press is recommended to ensure the desired results. Offset printers should consider the following tips:
Prepress: Imagery should be adjusted in prepress to compensate for the additional 5-15% tone value increase that will occur. The precise amount of under color removal is image specific. Total print densities should not exceed 280%. Remember that many of the prepress proofs have fixed compensated dot gain for coated stocks.
Ink/Ink Drying: Inks with more tack will give a firmer dot, so low-solvent, high-solid inks are recommended. Anticipate a dry-back of five to seven density points.
Handling: Keep heat transfer papers wrapped in mill packages until ready to print. Pressroom conditions should be as close as possible to 68°F and 45-60% relative humidity. Printing in smaller lifts is recommended.