From: Gary Jones (firstname.lastname@example.org )
Date: Mon, 08 Mar 2004 22:25:48
Your email raises some excellent questions regarding input material use per some unit of production. Unfortunately, there are very few answers for many of your questions. To the best of my knowledge, a database for most of the information you are seeking does not exist. Given the large variations in presses, product types, and workflows, it is difficult to define what a typical printer is or how much material a typical printer uses per unit of production. However, there is some general information that can be provided that may be of assistance.
1. Most blanket washes used by commercial printers are 100% VOC. It is important to understand that VOC content is not the only measure of the environmental impact of a cleaner. You must also look at the vapor pressure of it as well. Vapor pressure is a measure of the material's tendency to evaporate. Many larger printers will low vapor pressure washes, those with vapor pressures of less than 10 mm Hg at 68oF (20oC). Some nonheatset web printers and newspapers can use blanket washes that have about 70% VOC content with very little problems.
2. VOC content of fountain solutions range from zero to about 15%. Again, depending upon the type of press, dampening system, incoming water quality, water treatment, etc., the VOC content will vary. Some nonheatset and news paper presses can use 0% VOC containing fountain solution, while most larger commercial printers use alcohol substitutes that are about 3-5% VOC by weight. Smaller printers tend to still use IPA and can have up to 15% VOC content.
EPA and many states have established VOC content limits broken out by type of press and if refrigeration is used to reduce evaporation of the VOC.
The limits are as follows: Heat Set Web Presses
1.6% VOC, by weight as applied, when solution contains restricted alcohol (alcohol containing only one hydroxyl (-OH) and less than five carbon atoms) and is not refrigerated to 60Â°F or less; or
3.0% VOC, by weight as applied, when solution contains restricted alcohol and is refrigerated to 60Â°F or less. (Temperature of the reservoir must be monitored at least once every eight hour shift.); or
5.0% VOC, by weight as applied, when solution contains no restricted alcohol.
Non-Heatset Web Presses
5.0% VOC, by weight as applied, and solution must contain no restricted alcohol.
5.0% VOC, by weight as applied, when solution is not refrigerated to 60° F or less; or
8.5% VOC, by weight as applied, when solution is refrigerated to 60° F or less.
3. To the best of my knowledge, all of the inks used in the industry that contain less than 100 ppm of PB, CD, HG and CR, unless some special ink is needed.
4. There are no typical levels of silver in the effluent from printers. Many larger printers have eliminated silver by using direct to plate systems. Small printers still processing film are usually regulated by their local sewer authority and will have to treat their silver to meet the limit. Sewer code limits can range from 0.01 ppm to 2-5 ppm. Some sewer authorities have eliminated individual limits for silver as they have adopted the code of management practice, which requires the printer to recover a certain percentage of silver.