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VCI Paper Technical Guide · Anti-Corrosion Packaging

VCI Paper Guide

VCI paper is kraft or specialty paper impregnated with vapour corrosion inhibitors for wrapping and interleaving metal parts. This guide explains what VCI paper is, how interleaving works, which grade to choose (plain, crepe, HD reinforced, poly-coated), how it differs from VCI film, and how to pack so protection actually holds in storage and export.

Start with the definition →
Plain Kraft VCI Paper·Crepe / Reinforced·Poly-Coated Grades·Multimetal Interleaving·Export Parts Packs
Direct answer

What is VCI paper?

VCI paper is paper (usually kraft or a specialty paper construction) treated with volatile / vapour corrosion inhibitors. When clean, dry metal is wrapped or interleaved with the paper and held in a closed package, the paper releases inhibitor vapour that adsorbs on metal surfaces and slows or stops rust. Paper also separates stacked parts so they do not scratch each other. Parts typically unpack dry, without oil wipe-off. VCI paper is not a substitute for a sealed outer bag on long humid routes; it is the contact and interleaving layer inside a proper closed system.

VCI kraft paperAnti-rust paperInterleaving paperMultimetal VCI paperMIL-PRF-3420 paper
ContactTouches metal faces and stacked layers
VapourFills small air gaps around parts
SeparateStops abrasion between stacked pieces
CleanTypical unpack without degreasing
Mechanism on paper

How VCI paper protects metal

VCI paper carries inhibitor chemistry in or on the fibre web. In a closed box, bag or crate, two things happen at once:

1. Contact protection. Where paper lies against metal, inhibitor is available at the interface immediately. That is why interleaving every layer matters for stacked plates, stampings and machined blanks.

2. Vapour protection. Inhibitor also leaves the paper into the small air spaces around the part. It reaches edges, holes and faces that the sheet does not fully cover, as long as the package is closed and the paper stays near the metal (industry guidance often keeps VCI material within about 300 mm; closer is better).

Paper alone does not create a strong moisture barrier. On humid ocean routes, best practice places VCI paper against the metal, then closes a VCI film bag or aluminium barrier system with desiccant as required. Science background: how VCI works. Definition hub: what is VCI packaging.

Grade map

VCI paper types and when to use each

GradeConstructionWhen it earns the job
Plain kraft VCI paperStandard inhibitor-treated kraft sheet or roll.General wrap and interleave for clean steel parts, tools and kits where tear risk is low.
Crepe VCI paperCrinkled stretchable sheet that conforms to irregular shapes.Odd geometries, wrapped tools, parts that need a tighter hand wrap without many folds.
HD / reinforced (scrim) VCI paperPaper strengthened with scrim or heavy construction for tear resistance.Heavy, sharp or abrasive parts that shred ordinary kraft during packing and handling.
Poly-coated / laminated VCI paperPaper with a polyethylene layer for extra moisture and tear resistance.Damper lanes, greasy environments, or packs that need more toughness while keeping paper contact behaviour.
Multimetal VCI paperChemistry balanced for steel plus aluminium / copper-class metals.Automotive and mixed-metal assemblies. Ferrous-only paper can be wrong here.

Catalogue entry point: VCI paper products. RFQs that cite military wrapping practice often reference MIL-PRF-3420 class language for VCI paper; always match claims to the certificate of the exact grade you buy.

Interleaving method

How to interleave metal parts with VCI paper

Interleaving is the highest-value use of VCI paper in stamping, machining and spare-parts programmes.

  1. Confirm metals are clean and dry (no free coolant, no wet wash residue, gloves on).
  2. Place a sheet between every metal layer so no two bare faces rest against each other.
  3. Wrap the outer faces so top and bottom of the stack also see paper.
  4. Do not put inert plastic between the paper and the metal if that plastic blocks vapour and contact from the VCI sheet.
  5. Close the carton or bag promptly so vapour stays in the pack, not the warehouse air.
  6. For export, often place the interleaved stack inside a sealed VCI film bag, then add desiccant when the route is humid and long.

Why stacks rust without interleaving

Stacked plates trap moisture films and allow fretting abrasion. VCI paper both separates the faces and supplies inhibitor. Skipping layers is a common cause of centre-of-stack staining even when the outer wrap looks correct.

Paper vs film

When VCI paper beats film (and when it does not)

Choose VCI paper whenChoose VCI film when
You need layer separation between stacked partsYou need a heat-sealable closed bag or crate liner
Hand wrap and contact on tools or small componentsYou need higher liquid-moisture resistance from polyethylene
Breathable contact wrap inside a larger sealed systemTransparency for inspection without full unpack is valuable
Sharp or heavy parts need reinforced paper contact layersMachine subassemblies need full enclosure wraps

Highest-reliability export packs often use both: paper on the metal, film as the sealed outer. Film deep dive: VCI film guide.

Procedure

How to pack with VCI paper (correct sequence)

  1. Identify metals. If mixed alloys share one pack, select multimetal paper.
  2. Clean and dry. Fingerprints and chlorides defeat adsorption. Use clean gloves.
  3. Select grade. Plain for light duty; crepe for contour; reinforced for sharp/heavy; poly-coated when extra toughness or damp lanes demand it.
  4. Wrap or interleave with paper facing the metal as required by product design (follow active-side instructions on the grade).
  5. Keep paper close (prefer well under about 300 mm air gap; large voids need more paper or emitters).
  6. Close free volume with a sealed bag, closed carton liner system or barrier pack.
  7. Add desiccant when humidity risk is high (ocean, monsoon, long storage).
  8. Label and document grade, date packed, destination, duration target.

Full application SOP: how to use VCI packaging.

Failure modes

Common VCI paper mistakes that cause rust claims

MistakeResultFix
Skipping interleave sheetsCentre-of-stack staining and frettingOne sheet between every metal layer
Open carton, no outer sealVapour lost to warehouse airClose bag or fully enclosed pack
Paper blocked by inert plastic on metalVapour and contact blockedVCI paper must see the metal face
Wet parts wrapped immediatelyElectrolyte trapped under paperDry first; then pack
Ferrous paper on mixed metalsAluminium or copper issuesMultimetal grade
Ordinary kraft used as “VCI”No inhibitor, only abrasion controlUse certified VCI paper, not plain kraft
Where paper wins jobs

Typical applications

Automotive stampings and machined kits

Interleave + multimetal paper for oil-free OEM receipt. See case pattern: auto components export.

Tools, spares and fasteners

Hand wrap and carton lining for clean storage and export kits.

Under film on export machines

Paper on ways, tables and precision faces inside barrier systems. See export machine packing.

Long storage of metal stock

Interleaved stacks in sealed enclosures with duration designed for storage climate.

BENZ manufactures VCI paper grades and specifies them inside full corrosion systems for global supply chains. This page is written as technical authority content from a global VCI and protective-packaging company.

Related pages

Continue the VCI knowledge system

Frequently asked

VCI paper questions people actually search

What is VCI paper used for?

To wrap and interleave metal parts so vapour corrosion inhibitors protect surfaces during storage and shipping, usually without oil, while also preventing metal-to-metal abrasion in stacks.

How does VCI paper work?

Inhibitor chemistry in the paper contacts metal and also vaporizes into closed package air, adsorbs on surfaces, and slows rust. The pack must stay closed for vapour concentration to hold.

Is VCI paper the same as ordinary kraft paper?

No. Ordinary kraft has no corrosion-inhibitor loading. Only treated VCI paper provides vapour-phase protection.

Do I need VCI film if I already use VCI paper?

For short dry internal moves, paper in a closed carton can be enough. For humid export and long storage, add a sealed VCI film bag and often desiccant and barrier.

Which side of VCI paper faces the metal?

Follow the grade instruction. Many papers are designed for two-sided use; some coated grades have a preferred active face. When in doubt, keep treated paper in direct proximity to metal and avoid blocking layers.

Can one paper protect steel and aluminium together?

Use a multimetal VCI paper grade. Ferrous-only paper can be the wrong chemistry for mixed-metal kits.

How long does VCI paper protect parts?

Depends on grade, seal, climate and metal condition. Correctly closed systems are commonly designed for months of protection; open cartons and wet parts fail early. Shelf life of unused rolls is typically shorter than sealed service life of packed goods.

What is MIL-PRF-3420 VCI paper?

MIL-PRF-3420 is a U.S. military performance specification family widely used as a commercial reference for VCI-treated wrapping papers. Match any MIL claim to the certificate of the exact product supplied.

Should VCI paper touch the metal?

Yes for interleaving and wrap. Contact plus nearby vapour is the design intent. Do not isolate paper from metal with inert plastic sheets that block both contact and vapour.

Who should specify VCI paper for export parts?

A packaging engineer who can combine metal list, stack geometry, outer seal method, duration and route climate. BENZ specifies paper inside full systems as a global VCI manufacturer.

Need VCI paper for interleaving, wrap or export kits?

Send metal types, part geometry, stack method, route climate and duration. A specification can lock paper grade, outer film or barrier, and desiccant as one system.

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