DTG printing is best suited for 100% cotton garments. This is because the 100% cotton garments' natural fibers react better with the water based ink in DTG printers. The higher the cotton content, the more opaque the printing result.
Heather colours and cotton polyester blends have a textured look and blend two materials together. The range of polyester used is between 10% and 50%. As polyester is a synthetic material that repels water (often used in sportswear, for example), it naturally doesn’t interact with DTG’s water-based ink very well. Therefore, prints on cotton polyester blends tend not to have the same level of opacity as prints on 100% cotton garments.
Most hoodies and sweatshirts are blended with some level of polyester, even if they are solid colours, to achieve some sweat-wicking properties. Many customers who value the textured appearances of the heather colours more than print opacity would go for these cotton/polyester blends.
Triblends are made up of three different materials, a blend of cotton, polyester, and rayon. Rayon is a synthetic fiber made from regenerated cellulose, which does not work with the water-based DTG ink as well as cotton. Rayon material, however, is lightweight and improves the fit of a garment. Triblends also have a specific faded/vintage outcome with DTG printing.
In summary, for most opaque printing results, we recommend that you go with 100% cotton garments like solid colour t-shirts. If some trade-offs between print opacity and a specific heather colour look or a specific triblend fit are acceptable for you, cotton blends could be an attractive option.