Paper weight question. Gsm vs. lbs

[airdave]

Did I hear someone say "confusing"?

American measures are based on an English system.
English measures are based on a French system.

Just thought I would throw that out there to muddle the issue even more.

Here in Canada we use both and can't decide which is worse.

[SCEtoAUX]

Originally Posted by Yale

Sorry to be a spoilsport, but what's the source of this table and how accurate is it? The package of paper right beside me says that it is 67 lbs, or 147g/sq. meter. But the table correlates 67-lb. bond with 252gsm -- or 65-lb. cover stock with 176.83gsm. And if I try the numbers the other way, the table correlates 146.73gsm with 39-lb. bond or 54-lb cover stock. There doesn't seem to be any way to make the table equate 67 and 147, so can anybody resolve this apparent discrepancy?

That chart was obtained many years ago. It's origin is forgotten. I use a digital caliper to check out stuff. The measurements are close enough taking into account the inaccuracy of the instrument. The differences in the chart are most likely in the nomenclature used to identify the different types of papers.

A simple solution is if you don't like the chart then don't use it. What is so freakin' difficult about that?

[sharunas]

Originally Posted by Pgtaylorart

Sharunas, actually there was a recent thread by Plumdragon called "Allowing for paper thickness" that talked about exactly those issues. When I design in software and account for paper thickness it gets me much closer to an accurate build, but nothing helps more than actually test building the actual paper model. But at least I've solved 90% of the issues on the computer, then I can make minor adjustments and I'm done.

That's true, - "practice makes perfect"

Originally Posted by elliott

That thread is here

Allowing for paper thickness

Thanks Elliott.

[SCEtoAUX]

Originally Posted by SCEtoAUX

A simple solution is if you don't like the chart then don't use it. What is so freakin' difficult about that?

Well now that was a bit uncalled for.

The cardstock I use comes in a package that has 110lb/199gsm on it. Checking it with the digital calipers at numerous places shows it to be 0.21mm - 0.22mm thick on average which does correlate to 110lb Index on that chart.

The 65lb cardstock I use also has 176 gsm on the package. Checking it with the digital calipers at numerous places shows it to be 0.19mm - 0.20mm thick on average which correlates to 65lb Cover on that chart. The specialty 65lb cardstock with a metallic finish also measures out to those specs.

The 20lb Bond paper used has a thickness of 0.08mm - 0.09mm for one sheet which does not fit, but when 10 sheets are checked in a stack the reading is 0.097mm - 0.098mm which does fit.

The 24lb Bond paper used also states on the package that it is 90gsm and has a thickness of 0.11mm - 0.12mm which correlates to th 24lb Bond on the chart.

The 81lb/120gsm Text paper differs a bit. One kind has a white metallic finish called Crystal that measures out to around 0.12mm for a single sheet and around 1.2mm for ten sheets. However the grayish Lustre metallic 81lb/120gsm Text paper from the same company measures around 0.16mm for a single sheet and 1.57mm - 1.6mm for ten sheets which correlates to the information on that chart.

So basically that chart is accurate to within what would be acceptable limits. Paper manufacturers seem to differ in their production and accuracy of the information they provide for their products.

[airdave]

My 110lb cardstock is closer to .27mm
and my 65lb cardstock is about .23mm

(Both Wausau)

[Pgtaylorart]

Doug,
I very much appreciate your link to the chart, thanks for posting it. I've downloaded it and will refer to it often. The obvious problem with our US system is that there are basically 3 different measurements; cover stock, index, and tag(whatever that is). Paper weighs differently in each category based on density. But for our use this is irrelevant. We need to know the actual thickness and your chart is very clear about showing actual thickness. What I've been doing for my own use is measuring 10 sheets with a veneer caliper to get a more accurate reading and making the conversion from lbs to gsm. The only problem is finding paper here that lists both lbs and gsm. Wausau brand found at Kelly Paper in the US lists both on their paper. (Since asking my original question I've done some research and discovered this, but thank you everyone for your help!)
My very unscientific technique for building Leif's 1/33 laminated propeller involved taking 18 layers of paper and finding the thickness that best added us to the overall dimension needed (65lbs). Thanks again Leif for a very nice looking prop.

-George

[airdave]

I just came from the store...

They had both"Card"stock and "Cover"stock

Similarly packaged...65lb "card" and 67lb "cover"
(both 250 sheet packs, plain white smooth)
65lb was 176gsm
whereas the 67lb was 140 something gsm.

My assumption is both papers are about the same thickness.
But the Cardstock is more densely packed...resulting in a smoother finish.
And a slightly stiffer card.
This would explain the heavier weight.
Correct??

[SCEtoAUX]

I was thinking the same about the differences. One could be more dense than the other thus giving different measurements. The chart in question does not have a "cardstock" listing. Cardstock appears to be a generic term.

Here are a couple of reference sites for the chart I posted:

The Print Guide: Paper size and weight conversions

Paper Comparison

[airdave]

Card stock, as far as I know, is the stuff designated for "Business Cards"

maybe a smoother, stiffer version of "cover" stock for business card printing?

All I know is the cheaper "cardstock" you find at a place like Michaels
is not as stiff and as smooth as the Wausau "cardstock".
Its also not as bright white.

I keep both types of card for jobs of varying importance.

So I think the cheap "card"stock is actually "cover" stock.

[Pgtaylorart]

Right you are Dave, right you are. We just need to keep this thread alive until your famous monkeys appear, then we can put it to rest.