
plating, anodizing, & finishing Q&As since 1989
-----
GSM to Microns. Converting galvanizing weight to thickness

Q. CAN YOU PLEASE FURNISH THE ZINC GALVANIZING GRAM/SQ. METER EQUIVALENT IN MICRONS.
R YADAV- INDORE, MADHAYA PRADESH, India
2003
User's Guide to Hot Dip Galvanizing for Corrosion Protection in Atmospheric Service
by NACE
from Abe Books
or
Affil. Link
Your purchases make finishing.com possible
A. The density of zinc is 7.4 g/cm^3; there are 10^4 µm in a cm, so there are 10^12 µm^3 in a cm^3. Therefore 1 µm/m^2 is equivalent to 7.4X10^-4 g of zinc.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
A. Trevor, the danger in this type of calculations is that one gets confused about all the different dimensions. The calculation I use is (using dimensions that are commonly used in the world of coatings): Weight of coating/mtr2 [grams/m2] = Film thickness [µ] x specific weight [grams/cm3].
In the case of Zn: specific weight is 7,4 grams/cm3: Zn weight/sqm = 7,4 grams/µ
Calculation is applicable with any coating, p.e. powder:
How much powder is on a part of 3 m2 with an average DFT of 80 µ and a specific weight of powder of 1.3 kg/dm3? Answer: 80 x 1.3 x 3 = 312 grams.

Remmelt Bosklopper
- Enschede, The Netherlands
A. I can Simplify the calculation method for converting gr/m2 to micron or micrometer.
D(density) = Wt. (weight)/ V (volume)
for Zinc
D = 7.4 g/cm3
= 7.4/cm*cm*cm.
1 cm = 10000 micron or micrometer.
= 7.4/cm*cm*10^4 µ.
so:
10^4 µ = 7.4 g/cm*cm.
1 m = 100 cm.
10^4 µ = 7.4 g*100*100/(100*cm)*(100*cm).
10^4 µ = 7.4 g* 10^4/m*m.
1 µ = 7.4 g/m2 for one face.
1 µ = 14.8 g/m2 for two face.
ex:
for galvanization layer
25 µ = 185 g/m2 for one face
and 25 µ = 370 g/m2 for two faces.
Kandil Steel - 10th of Ramadan - Egypt
August 25, 2014
Q. Many of my customers are asking that you says it's 90 GSM, but can you tell us in microns, and at this time I can't answer, so please let me know how to calculate micron to GSM and vice versa
R.Ashok Gour- CHENNAI, Tamil Nadu, India
May 2, 2019
"Handbook of Hot Dip Galvanization"
by Maass & Peissker
from Abe Books
or
Affil. Link
Your purchases make finishing.com possible
A. Hi Ashok. They can measure the thickness of the galvanizing with a magnetic thickness meter if they wish confirmation.
Remelt has told us that 1 micron is about 7.4 GSM; so 90 GSM would apparently be somewhere around 12 microns. However, as Nagy implies, it is conventional that 90 GSM refers to the total amount of zinc applied to both sides of the strip, so I would expect the thickness to be about 6 microns per side.
You are welcome to refer them to this page where the question has been answered. Good luck.
Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Most sources give the density of pure zinc as 7.14 g/cc. It will be slightly higher for Prime Western Zinc which is a zinc-lead alloy (up to 1.4% lead) but not much. The vast majority of hot dip galvanizing, until recently, was done with Prime Western Zinc. Other alloying components (aluminum, nickel, etc.) will have calculable effects on the density of the coating.

Tom Rochester
CTO - Jackson, Michigan, USA
Plating Systems & Technologies, Inc.


Thanks for the more refined answer, Tom. 90 GSM equals about 13 microns.
Regards,

Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
![]() |
Q. If I have paper that is 32GSM what would be the approx. micron thickness. Anthony CuschieriInternational Packaging Films (PET Film)s - Norwood, New Jersey USA July 24, 2019 A. Hi Anthony. I don't know much about paper (this page is about galvanizing and the site's main focus is metal finishing), but a roll of coated magazine paper weighs far more than an equal size roll of toilet paper. So I think your question isn't answerable because the density of different papers can apparently vary by 4:1 and probably more. ![]() Ted Mooney, P.E. RET Striving to live Aloha finishing.com - Pine Beach, New Jersey |