Kraft->GSM Conversions

[Mephistos Minion]

Gday,

Wasn't sure if this belongs here, but I don't want it to get lost in the forums , so I decided here it would go, mods, if you want to move it go ahead.

 

I did all the calculations and here is a fairly accurate table of Kraft weights to GSM (Grams Square Metre commonly used outside the USA)

 

30lb Kraft = 50 GSM

40lb Kraft = 65 GSM

50lb Kraft = 80 GSM

60lb Kraft = 100 GSM

70lb Kraft = 115GSM

 

If you have another weight then here is the formula using 70lb as an example:

 

70/500 = 0.14

0.14 x 457= 63.98

63.98 x 1.8 = 115

 

The reason it is this is: The weights for Kraft are determined by a stack of 500 24"x36" sheets (61cm x 91.4cm). So therefore each sheet weighs 70/500lbs (63.98g) because theese sheets are less than a metre square we must times by 1.8 to get it there (61 x 91.4 = 5575.4) so then 5575.4 x 1.8 = 10035 ( 1 square metre is 10000, ok its a little off but close enough if you are after standard GSM Kraft paper get the closest one). So we must also multiply the weight of the 24"x36" sheet by 1.8 to get the GSM (63.98 x 1.8 = 115.164) and there you have the weight of a meter square of 70lb Kraft. Just drop your number in place of the 70 to work out other weights not listed in the chart.

[Chris]

That was helpfull. Thank you!

[Givat]

Thank you.

 

And if your calculations are correct you can just take the weight of the kraft paper as X:

X(lb)*1.645 = weight in GMS

 

(just looks shorter that way )

[pudidotdk]

How do I know, if I have a random piece of paper, how many lbs it is?

[Pretty green flame]

How do I know, if I have a random piece of paper, how many lbs it is?

Cut out a square measuring 10x10cm, you then weigh it (obviously the scale should be accurate to atleast 1/10th of a gram). Since the patch of paper is 100times smaler than one square meter you multiply the weight by 100 so you get g/square meter.

 

Also, different weights of paper have different thicknesses so if you have some calipers handy you could measure the thickness of 10 papers and divide by 10 to get the thickness of one piece. Somewhere on the net there should be a chart for this stuff.

[pudidotdk]

okay a 10x10 cm sheet weights 1,2 g and is ~0.2 mm/0.007"

 

Guess this makes it 70 lbs, which I was hoping for.

[TheSidewinder]

Since you asked what the weight would be in pounds, just measure the thickness. (30# paper is .0030 inches thick, 40# is .0040, 70# is .0070, etc.)

 

No need for fancy math.

 

M

[Aquarius]

Pudi, have you gotten hold of Virgin Kraft in DK?

I'm trying to find some where I live, but no luck so far..

[pudidotdk]

Pudi, have you gotten hold of Virgin Kraft in DK?

I'm trying to find some where I live, but no luck so far..

Nah, not Virgin.

Havn't got any luck finding it, this was the kraft used for covering when painting etc. Looks like nice brown kraft on one side and a little more grey/recycled on the other side.

[Aquarius]

Using the same stuff myself, cheap as chips, but I am afraid the holding force of these kraft-based tubes might not be enough. They seem inferior to manilla folders.

 

But I am in contact with a reseller in the US who will ship virgin kraft (or so he claims) internationally, and I'll probably go for his offer.