Digital BW, The Print

>Message: 19
>   Date: Wed, 20 Nov 2002 13:54:43 +1000
>   From: "Peter Marquis-Kyle" <petermk@...>
>Subject: Re: ESFA In a 3000
>
>Thomas Keesling wrote:
>> Mark wrote:
>>
>> <<The actual thickness of those papers you mentioned can be a bit
>> misleading....I've never fully understood how papers get rated...>>
>>
>> I'm baffled, too, and wish there were a better way to categorize
>> them. I suppose the ideal would be to have both the weight and the
>> caliper readily available on all papers.
>
>Might we need to specify another parameter? Call it 'stiffness'
>perhaps?
>
>I can imagine two papers with the same weight and thickness -- one of
>them stiff, and the other one limp.
>
>Peter Marquis-Kyle
>________________________________________________________________________
>________________________________________________________________________
>Message: 24
>   Date: Wed, 20 Nov 2002 08:40:32 +0100
>   From: "Ernst Dinkla" <E.Dinkla@...>
>Subject: Re: ESFA In a 3000
>
>
>----- Original Message -----
>From: "Thomas Keesling" <tom.keesling@...>
>To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
>Sent: Wednesday, November 20, 2002 2:34 AM
>Subject: [Digital BW] ESFA In a 3000
>
>
>> Mark wrote:
>>
>> <<The actual thickness of those papers you mentioned can be a bit
>> misleading....I've never fully understood how papers get rated...>>
>>
>> I'm baffled, too, and wish there were a better way to categorize them. I
>> suppose the ideal would be to have both the weight and the caliper readily
>> available on all papers.
>
>The best way is still "grams per square meter". Paper manufacturers then add
>in Dutch "opdikkend" what roughly translates to "thickened" when the paper
>gets more volume at the same weigth. And even that doesn't cover all the
>tactile differences between papers. A stronger sized paper will show more
>rigidity, a hot pressed paper will be more flexible. Any offset printers
>paper catalogue will have those specs added,
>it is unlikely that that will happen with inkjet papers soon.
>
>Ernst

Hello All!
Speaking from the paper manufacturing side of things, paper makers have
various parameters under which they control paper being made. With respect
to weight, we [that is, paper makers] look at basis weight, density, and
caliper.  

Basis weight is measured in grams per sq. meter (gsm), which in my opinion
is the best way to measure paper.  However, starting in the UK, and
continuing here in the US and Canada, paper makers developed different
"bases" for weighing paper--bond, text, and cover.  these basis weights are
calculated on the amount of sq.ft. per ream of paper.
EG, bond= 1 ream equals 500 sheets of 17x22 paper, or 1300 sq ft
    text= 1 ream equals 500 sheets of 25x38 paper
    cover= 1 ream equals 500 sheets of 20x26 paper

in order to know the true "weight" of a paper, one must really know the
basis weight (in lbs. or gsm), the density, and the caliper (measuremed in
mils of inches or mm).  

Having worked at Crane, and helped to develop the Museo/ESFA program, i
know that caliper, density, and basis weight were part of published specs,
and should still be on the Museo web site.  All paper makers and
distributors should have this information available at their fingertips at
a moment's notice.

i hope this info helps y'all in comparing different papers to each other.
thanks
Robert Rex
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