7 vs 10 mill mylar cover sheet for Vandercook
The top sheet that we have on our Vandercooks is 7 mill mylar. I notice that Talas has rolls of both the 7 mill and 10 mill mylar.
Although I don’t see any impact on printing quality the 7 mill will show indents when we’ve run a particularly large edition.
I was wondering if anyone had an opinion that the 10 mill might be better to use.
Lead
Some thoughts and practices:
I suspect the 10 mil might be a bit stiff and might not conform as comfortably to the cylinder.
I’ve run 5 mil for years and I rarely have to replace it. I’m using 21 mil Kimlon directly under it though and that might absorb some of the impression shock.
Beneath the Kimlon are whatever required treated sheets are need for the packing. At least one bottom treated sheet is necessary to prevent the cylinder from rusting. The bottom sheets, oddly enough, seem to reveal where impression strike has occurred, more through surface marking rather than indention though. These I change out per job.
I also routinely use 2 mil Riegal untreated press pack stretched taped directly to the Mylar to prevent it from burnishing the printed sheet at impact. And that may as well prevent damage to the top sheet.
I guess this is what would be called a hard, yet resilient, form of press packing.
This configuration has worked out well for me and eliminates a lot of change over. I recall reading an article by Claire Van Vliet where she mentioned that after twenty years of printing she was on her third tympan. Impressive :—) She has now been edition printing on Vandercooks for over half a century. The grand mother of us all.
Gerald
http://BielerPress.blogspot.com
Hhhmmm… I thought my grandmother’s name was “Grandmother” ;)
Lead-Graf- If you are getting dents with 7 mil, I’d look at the packing beneath the mylar….. or at your lock-up. If your lock-up is good, you should not be getting many dents. But if you have bits and pieces that are a little higher than “type high” you can dent the mylar on the first impression.