The Speedball Water-Soluble Block Printing Ink Retarder will slow down the drying process when mixed with water-soluble block printing inks, so you can work on your project at your own speed. It comes especially in handy when working in warm and/or dry climates. The retarder will not change the viscosity of your ink and is suitable for block and linoleum printing. This water-soluble block printing ink retarder has excellent transfer tack which ensures even coverage and produces minimal odor. This ink retarder can only be mixed with water-soluble printing ink. The Speedball Water-Soluble Block Printing Ink Retarder is gluten free and ACMI AP Certified so it is safe for everyone to use both at home and in the classroom.