I once saw an advert for an ink draw-down apparatus and now I cannot find it again. The “knife” ran along a track and was adjustable so you could, via trial and error, work out a setting that most closely resembled the amount of ink actually deposited by your press. Does this ring a bell with anyone?
Log in to reply 6 replies so far
I vaguely remember something like that, but let me run this by you:
There are several variables in the process of making a drawdown. The angle you hold the blade at, whether you use a slightly flexible or rigid blade, and how much pressure you put on the blade, are three variables. However, as long as you are within a range, these should not affect the drawdown too much. Another reason why they will not cause variation in your drawdowns is that after you make a lot of drawdowns (i.e. a hundred plus), you will get in the habit of doing it the same way every time, without even thinking about it.
What WILL affect the drawdown is what paper you use. The coarser the paper, the more ink you will put down, because the ink fills the little voids in the rougher paper. If I was going to try to duplicate what I do on the press, I would experiment with papers having different degrees of roughness.
Once you have found your “standard drawdown paper,” use that paper every time. Don’t try to make a drawdown on a different type of paper because that is the paper you are going to print the job on.
If you want to do this, I hope you can make it work, but it is not the way the industry usually predicts what the color will look like on press.
I don’t understand why you wouldn’t always do the drawdown on the stock that will actually be used for the job.
Because often, a drawdown on a rough paper will not appear very close to how ink transferring from plate to paper will appear. It is not necessarily a direct correlation unfortunately. Would that it were so easy…
Drawdown is a process that uses Sheer to apply the ink- meaning the scraping action applied. It doesn’t stamp a transfer of the ink to the paper, rather it rubs against the surface of the paper. These are very different actions and if you are laying ink down with letterpress, it’s even different from some other printing actions that are available out there.
Coatings are VERY fussy things to work with.
Come to think of it- one might be better off making a small circular rubber stamp and picking up the ink/applying it with this stamp in a row of stamps. Pick up some ink, stamp; stamp; stamp; stamp; stamp.
Later, See which one winds up being closest to the actual transfer of ink on press.
Or better yet, make a stamp out of polymer and try testing with it.
Drawdowns are still best for predicting hue, but they seldom nail the density of the ink/opacity, anyhow.
Having once worked as a salesman for Borden Chemical printing ink division I will add my knowledge to this string.
We would do ink draw downs in several ways.
1. This was done to test the transparency or opacity of the ink. Done with just an ink knife of a strip of paper with a printed black dot on the paper. A small amount of ink is cut in half with the blade of the knife an drawn over the printed bar or spot.
2. A small bar with a hole is filled with the ink. It is pushed out with a pin. This ink is spread with a brayer and the is rolled out over strips of paper, I think at least two to three times. The second or third print is the ink color.
3. A tap out. Taking the tip of one’s finger you slowly tap out the ink in a circular pattern on the paper, after about 4-5 finger taps out without going back to the original ink spot should be the color of the ink.
If you want to get serious, you could look at byk.com for more than you might want to know about drawdown tools. They have prepared drawdown cards. I suspect that using the actual paper that you intend to print on would be a reasonable expedient, as suggested above. So most of their products are aimed at manufacturers of coatings rather than users of coatings, but if you want to geek out on the subject, this would be a great place to start.
And at several thousand dollars for the most minimal drawdown device they sell… Hardly a hobbyist’s endeavor ;-)
Here’s a “deal” on one on ebay, for $2125.00: