VCI Paper Grades & Types
VPI VCI VCPI VPN MPI VpCI Paper Continued.....
As we discussed in our previous article on the branding of VCI paper manufacturers typcially come up with their own branding to describe their brand of corrosion control paper. This article further explores the key elements for success using VCI Paper for corrosion protection in packaging.
The VCI paper grade that works best for corrosion protective packaging of machinery, parts and equipment is determined by the type of metal that requires corrosion or rust protection, the anticipated environment and the length of time the metal is to be preserved. This is why it is important to have some understanding of VCI paper grades. When referring to a VCI paper grade the component features are intended use and construction.
Intended Use of VCI Paper
In addition to preventing corrosion in metals you need to know the following to determine the grade or type of VCI paper to use for your application:
1. Type of metal(s) you are shipping?
2. How long in months or years do you need to preserve the metal? Shipping & storage time.
3. What environment will the package be subjected to... during this time? Export or domestic? Coastal area?
4. Are there any oils, residues, machine coolant or soils on the metal surface?
From the answers to the above questions an experienced professional can help you to determine the best protection system for your corrosion control plan. Note that the longer the period of protection, the greater the cost. For periods extending past 2 years, a combination of VCI paper and additional materials is usually recommended.
There are several types of VCI paper, for example:
VCI paper for a specific type of metal.
Ferrous-cast iron & steel, non-ferrous, aluminum, copper, silver, galvanized...
VCI paper for combinations of metal types
VCI paper of the type(s) above with additional poly, wax, other vapor barrier backing or a laminate construction
VCI paper as in any of the three descriptions above PLUS a reinforced construction for additional tear strength
The last two types in the list above enter into the realm of construction of VCI packaging materials. VCI paper can be constructed in different thicknesses and with additional materials 'bonded' to the paper for increased long term corrosion (rust) protection. Different constructions are also made for rust protection in aggressive or extreme conditions. Both the paper and the additional vapor barrier can be of different thickness depending upon the needs of the particular application. Paper thickness is measured in pounds/ream or kilograms/square meter. The thicker the paper the more physical damage protection in provides to the wrapped parts. The thicker the addtional bonded layer or laminate then the more vapor barrier protection is provided by the paper grade.
VCI Paper Thickness
Typcially paper thickness is referred to as basis weight, in pounds per ream. The English & Metric System uses a scale of grams per square meter. In the United States, the weight in pounds of one ream of paper that is cut to the basic size (or trade size) for a specific paper type. For industrial VCI paper a ream is 3,000 square feet of paper. Most industrial VCI paper sold today will be 30 pounds/ream or more. It is written 30#, 44#, 60# etc. to describe the paper thickness. It may be noted as 35#, 35/57*, 35 lb, and so on. Popular thicknesses of VCI paper used in industry are 30#, 35#, 40#, 50#, 60# and 70# VCI Paper. Most being in the 30# to 40# range as the protection period is relatively short-less than one year.
* 57gsm = 57 grams per square meter = 35 lbs per reem (The conversion factors are shown below:)
Trade Size Basis Weight to Grammage Grammage to Basis Weight
3000 sq. ft. 1.6275 x lb. = gsm 0.61445 x gsm = lb.
The important thing to know about VCI paper thickness, is that the higher the basis weight, the greater the thickness of the VCI paper.
When selecting corrosion protective packaging, providing your supplier with the basic information described in list points 1 to 4 above, regarding the shipment or storage, are key components of the VCI packaging selection process. For help with your packaging design you can also fill out this form: VCI Packaging Selection Form Additionally many packaging projects use VCI paper chips for additional corrosion protection inside the packaging.
Resources Used for this Article: Mil-P-3420 VCI Paper VCI Paper Catalog Packaging Design for Corrosion Control Export Packaging Systems VCI Paper Store VCI Paper Chips