Doctor blade and doctor blade flaws

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Robinr
Posts: 155
Joined: Fri Aug 27, 2010 6:00 pm

Doctor blade and doctor blade flaws

Post by Robinr »

Dear All,

On a current thread on booklets there are two apparently totally conflicting statements - from people who know their stamps very well. I hope they'll forgive me paraphrasing:

1. Those vertical ink lines that pop up now and then on pieces, blocks, etc., are (and are invariably referred to as) doctor blade flaws.

2. If the line is vertical it cannot be a doctor blade flaw. These flaws are sloping or slanted because the blade wipes the cylinde sideways as it rotates.

Could somebody please explain exactly what the doctor blade does, and which of these statements is correct? There must be a LOT of dealers misdescribing choice blocks, and a lot of misguided write-ups one way or the other.

Or are they both right?

Thanks a ton, Robin R.
Barry_Smith
Posts: 7
Joined: Wed Oct 06, 2010 6:00 pm

Transfer from previous board: original post 1459

Post by Barry_Smith »

There is a description of Doctorm Blade Flaws at http://www.thetenoclockshow.co.uk/compo ... Itemid,54/

The flaw can be either horizontal or vertical on the pane (depending on the direction of printing) AND always slopes, but so little it is very hard to detect. If you have a number of consecutive booklets with the faw it is easier to see the slope when you put them all together.

The Doctor Blade itself is very well described at http://pdf.polestar-group.com/elearning ... rblade.pdf
Robinr
Posts: 155
Joined: Fri Aug 27, 2010 6:00 pm

Transfer from previous board: original post 1462

Post by Robinr »

Hi Barry,

Many thanks for a prompt and totally helpful explanation!

So, both are right! The line APPEARS to be vertical but is in fact slanted, and is vertical on upright-printed sheets and sideways on sideways-printed sheets.

I like the idea of collecting from the same sheet to see how far the flaw extends. I wonder whether that resulted in somebody buying dozens or hundreds of the cookbooklets!

Cheers, Robin Restall
robinT
Posts: 88
Joined: Fri May 08, 2009 6:00 pm

Transfer from previous board: original post 1464

Post by robinT »

I have seen complete sheets with more than one doctor blade flaw on - from top to bottom.

Quite obviously 'printers waste' which 'escaped'

Ber very careful going down that road.
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