Questions :
For answers please click on the questions

1. What is the exact mechanism of VCI?

2. Is there any type of coating on the film?

3. What is the difference between VCI paper and CAPRUST film?

4. What is the shelf life of CAPRUST VCI film?

5. Is there a relationship between the Moisture Transmission Rate of a film and its ability to inhibit corrosion?

6. Is there a relationship between the thickness of a CAPRUST VCI film and its ability to inhibit corrosion?

7. What are different styles of package Caprust can be available?

8. What is shelf life of CAPRUST film stored open to the air?

9. What is the best way to store CAPRUST films before use?

10. How long does it take for the interior of a VCI package to reach saturation?

11. How should VCI films be stored?

12. How long does the protection last?

13. Is there any necessity to create artificial environment for the storage of VCI bags?

14. Is there a prescribed distance from a part that a CAPRUST VCI material must not exceed; otherwise the CAPRUST VCI will not protect the part?

15. Can VCI be effective in ambient climate?

16. Do CAPRUST films emit vci molecules from both sides?

17. Vapors give any residual spots on metals?

18. Do CAPRUST VCI vapors have any effect on electrical or electronic components?

19. How to clean the material after it is removed from the VCI bags?

20. How long can parts be expected to remain free from corrosion after unpacking from a CAPRUST package?

21. What are different types of sealing that can be done in VCI package?

22. Which metals can be protected against corrosion using CAPRUST film?

23. Whether shelf life of film is different for different metals?

24. Is there a text method to determine if a CAPRUST VCI film is still emitting VCI vapors?

25. What are the advantages of the following CAPRUST packaging alternatives and which is best?

26. Are there disadvantages associated with CAPRUST products?

27. How does moisture in a package affect CAPRUST VCI protection?

28. When the desired period of protection is one year, would it be possible to reduce the percentage of the VCI masterbatch to achieve this?

29. Are there any examples where plain polyethylene film can be combined with CAPRUST film to provide better overall protection from corrosion?

30. How is the quality of CAPRUST film determined?

31. What method is recommended for packaging small parts?

32. Corrugated cardboard sheets are often used to separate one row of parts from another in a package. These sheets will absorb moisture in storage and transit and will induce corrosion on part surfaces in contact with the cardboard. How can this be avoided?

33. What are the differences between monoextruded CAPRUST VCI films and coextruded films where one side only contains a VCI formulation?

34. Are there any inhalation or contact risks with CAPRUST films?

35. Whether printing can be done on VCI film?

36. Can vaccumising cause any effect on the film?

37. Is package highly flammable?

38. Are CAPRUST films cost effective?

39. Can CAPRUST film be recycled from CAPRUST scrap?

1.What is the exact mechanism of VCI?

A.VCI vaporizes and migrates to all recessed and cavities and thus form a thin monomolecular protective layer and acts as a barrier against rust.

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2.Is there any type of coating on the film?

A. No there is no coating on to the film; inhibitors are basically impregmented in to the film.

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3. What is the difference between VCI paper and CAPRUST film?

A. There are many benefits of film over paper. The film gives a more stable polymer matrix for the VCI chemical giving longer and more powerful performance. The film has superior tear strength and can be sealed to form a protective enclosure around the metal part. Paper absorbs humidity and quickly becomes ineffective. Paper can be cheaper and is useful where 'wrapping' is required. Please go through the module 'comparison' on our site to study the same.

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4. What is the shelf life of CAPRUST VCI film?

A. The films emit corrosion inhibiting molecules for 5 years. The actual length of protection can be more or less than this depending on the packing and service conditions. But shelf life of the film is about one year without affecting the length.

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5. Is there a relationship between the Moisture Transmission Rate of a film and its ability to inhibit corrosion?

A. There is a direct relationship between the two, the less moisture the VCI formulation has to deal with; the better would be the overall protection of the package.

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6. Is there a relationship between the thickness of a CAPRUST VCI film and its ability to inhibit corrosion?

A. Since a thicker film offers greater resistance to moisture transmission, one should expect better protection from a thicker film. We recommend the thickness of the film to be 400 to 800 gauge for better protection.

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7. What are different styles of package Caprust can be available?

A. Individual bags for parts, large bags for lining crates, hoods, sheets, covers and films are produced in regular, shrink, stretch and type materials.

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8. What is shelf life of CAPRUST film stored open to the air?

A. Following are the possible situations, which are to be considered.
Example 1 : An exposed sheet of CAPRUST film.:-In this example the sheet's life span would be directly influenced by its surrounding temperature.

Example 2 : An exposed roll of CAPRUST film.:-In this example only the exposed portion of the roll would be directly influenced by its surrounding temperature but not the interior surfaces of the roll.

Example 3 : CAPRUST film stored unexposed, i.e. in plain wrappers, cartons, etc. The shelf life of the film in these conditions is essentially unlimited. This is because the film will emit VCI vapors until the interior of the package is saturated, at which time vapor emission will cease. In these conditions the consumption rate of the VCI molecules due to the presence of moisture is reduced to essentially zero. The film will have no need to replace consumed VCI molecules and therefore will cease its emission of VCI molecules. It has thus been proved that when covered in storage the CAPRUST film enjoys a longer shelf life.

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9. What is the best way to store CAPRUST films before use?

A. It is a good practice to keep CAPRUST films clean in storage. Simply keeping the films in their shipping cartons or covering the film with a sheet or bag of plain polyethylene film will suffice.

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10. How long does it take for the interior of a VCI package to reach saturation?

A. The time required for saturation depends on the volume of VCI and temperature of the package. Protection begins as soon as VCI vapors reach metal surfaces, and maximum protection is achieved when total saturation of the package is reached. The time required to reach total saturation is shortened when temperatures are higher. Saturation time in a typical factory environment and in a typical CKD packaging application can run from 12 to 24 hours.

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11. How should VCI films be stored?

A. It is preferable to ensure that VCI films are kept as clean as possible. It is thus a good practice to store unused VCI films in factory pack conditions

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12. How long does the protection last?

A. Tests performed with electron scanning instrumentation show that after 2-4 hours all traces of VCI disappears once the part is removed from the VCI package.

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13. Is there any necessity to create artificial environment for the storage of VCI bags?

A. No there is no such need to create artificial environment.

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14. Is there a prescribed distance from a part that a CAPRUST VCI material must not exceed; otherwise the CAPRUST VCI will not protect the part?

A. VCI's release molecules because the VCI molecules have a vapor pressure (energy) higher than the pressure of the surrounding air (14.7 lbs/sq. in.). Once the VCI molecules enter the air the only way they move is by diffusion, that is the air currents that are caused by rising and falling air temperatures. This is the same natural process whereby dust particles move about a room. The VCI molecules don't just jump from the VCI film and stop. CAPRUST films are used successfully on CKD applications where the crate measurements are 2m x 2m x 4m. Caprust VCI film attracts upto 2m provided there is no other barrier between the material to be protected and the Caprust film.

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15.Can VCI be effective in any ambient climate?

A. VCI can be effective in any kind of climatic condition.

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16. Do CAPRUST films emit vci molecules from both sides?

A. CAPRUST emits VCI molecules only when it's come in contact with metals.

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17.Vapors give any residual spots on metals?

A. Caprust does not leave any residue of VCI on the component to be protected. As it has adsorption properties and not absorption.

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18. Do CAPRUST VCI vapors have any effect on electrical or electronic components?

A. Test data available from IIP proves that CAPRUST VCI films do not adversely affect electrical and electronic components. As VCI attracts only metal, it does not adversely effect any other component.

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19.How to clean the material after it is removed from the VCI bags?

A. Component packed in our bag remain fresh and in mint condition, further as for the coating is considered same can be consulted to C.E.D coating manufacturer.

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20. How long can parts be expected to remain free from corrosion after unpacking from a CAPRUST package?

A. Customer tests using electron scanning techniques show that after approximately 3 hours of removal from a VCI environment all traces of the VCI molecules are gone from an item's surfaces. With regard to the period of time before one can expect corrosion of a part it depends heavily on the cleanliness of the part and the condition of the atmosphere around the part (relative humidity, presence of pollution, temperature, etc.)

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21. What are different types of sealing that can be done in VCI package?

A. CAPRUST films require heat sealing for better results. Smaller bags may have their openings simply folded over, stapled or taped shut. Larger bags, for example those used for automobile engines, may be closed off with a tie wrap or heat sealed. CAPRUST bags used as liners for large wooden crates or corrugated cardboard cartons may simply have their openings folded over, it would also be advisable to vacuumise the bag. In all cases the main objective is the same
a) to ensure that any air entering the interior of the bag comes only through the sides of the bag and
b) all traces of VCI disappear from the surface.
Basically impulse heat sealing process is used to seal the bags and big covers are being seal by manual bar heat sealing process.

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22. Which metals can be protected against corrosion using CAPRUST film?

A. Almost all commonly used engineering metals can be protected. There are three main types of film known as Ferrous, Multi-metal and Non-Ferrous. We only specify a Caprust product after carefully evaluating an application.

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23.Whether shelf life of film is different for different metals?

A. Shelf life of film is not different for different metals.

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24. Is there a text method to determine if a CAPRUST VCI film is still emitting VCI vapors?

A. There is a short version of IIP method that can be used to determine whether a used or old VCI film is still functioning satisfactory. This simple test requires the submission of necessary samples to the laboratory.

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25. What are the advantages of the following CAPRUST packaging alternatives and which is best?
a. Parts + CAPRUST
b. parts + anti-corrosion liquid + CAPRUST
c. parts + anti-corrosion liquid + CAPRUST + strong barrier material.

A. All of the listed packaging alternatives can provide satisfactory protection. The decision as to which is best for a part depends on such factors as:
a. what physical conditions will the package be expected to endure?
b. what atmospheric conditions will the package be expected to endure?
c. how long will the package be expected to protect the part in storage?
d. how is the total package to be constructed?
We believe it would be misleading to simply choose one alternative over the others without taking all possible influences on the alternatives into account. For example, a machine engine block in a CAPRUST bag shipped on a wooden pallet in a truck is not the same as a machine engine block in a CAPRUST bag shipped in a steel container by ship from one hemisphere to another and then transported by truck to its destination. Our main objective is always the delivery of parts in a clean, dry and corrosion free condition, i.e., without the use of coatings. If anti-rust oils are used together with CAPRUST products then one is putting CAPRUST inhibitors in a secondary or supporting role. The oil assumes the primary responsibility for the protection from corrosion of the product, since the CAPRUST vapors cannot reach the surfaces of the part. Over time, however, oil can drain from the part and the coating can become so thin that it "cracks" and without a secondary source of protection corrosion will begin. Of course the oil selected can be so heavy and viscous that the possibility of the oil thinning to the point of cracking can be essentially eliminated, but such types of oil are difficult to obtain and costly. The addition of a reinforced outer wrap , of course, increases the resistance to moisture in vapor and bulk form, as well as the resistance to physical damage. It also effectively extends the life of the CAPRUST VCI indefinitely since a static saturation of the interior of the package is reached and consumption of the VCI ceases. This type of package is the most durable and effective but it is certainly the most costly in terms of time and materials to prepare. If care is taken in the design and preparation of the package to limit physical damage of the packaging material and if part surfaces are maintained in an appropriately clean condition then the "part plus CAPRUST " alternative will protect satisfactorily and this is certainly the most cost effective alternative of the three alternatives.

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26. Are there disadvantages associated with CAPRUST products?

A. The answer to this question is influenced by the characteristics of the corrosion inhibiting alternatives to CAPRUST, the objectives of the packaging engineer and how much the packaging engineer is willing to spend for a packaging solution.
Consider these examples:

Example 1 : VCI capsule versus desiccant.
A test was performed at a nuclear power facility wherein a CAPRUST Vapor Capsule and a bag of desiccant were compared in the protection of the interior surfaces of spherical steel vessels. The vessels were stored outdoors in summer conditions. The results showed that both products protected the vessel's interiors provided, however, the desiccant was removed from the vessel every third month and dried in an oven. This made the desiccant solution the more costly of the two; a disadvantage. The desiccant also required someone to schedule the drying of the desiccant; a disadvantage. If the engineer missed one drying cycle corrosion could be anticipated; a third disadvantage. The Vapor Capsule had none of these disadvantages.

Example 2 : Oiled Engine Blocks. A test was performed on a machine engine block packaged for international sea shipment using CAPRUST bags. The company wanted to ship the blocks in a dry condition rather than in a very heavily oiled condition, which was the existing protection method. The final steps in the block's processing were a washing and drying operation. The company found, however, that their drying equipment and procedure could not ensure a sufficiently dry block for VCI protection. Water, in bulk, was never removed from the tapped block holes and the blocks experienced corrosion in the holes, but nowhere else. The heavy oil dealt successfully with this condition but the VCI's could not. The problem was solved by using a light oil, which by itself was not enough to completely protect the block, plus a CAPRUST bag. The test showed that the company's drying procedures were disadvantageous for them as it disallowed the unassisted use of a VCI product. The company was not inclined to install new drying procedures which put CAPRUST film at a disadvantage. However, the presence of CAPRUST film did permit a lighter oil to be substituted for the less desirable present oil. This oil was easier to apply and remove, thereby creating a more advantageous position for the company.

Example 3 : Fingerprint Corrosion.
VCI's do not inhibit corrosion caused by fingerprints on metal surfaces. Only specially formulated oils will lift fingerprints from surfaces. The use of VCI's requires workers to wear gloves.

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27. How does moisture in a package affect CAPRUST VCI protection?

A. Packaging films for industrial applications are produced from low and high density polyethylene resins and therefore are resistant to moisture to some degree but not completely. Atmospheric moisture will eventually find its way into a film bag. The presence of moisture in a bag can be expected on surface shipments, particularly shipments crossing the equator. CAPRUST films will inhibit moisture entering a bag provided that the moisture enters the interior of the bag through the film. Corrosion problems arise when moisture is allowed to enter a CAPRUST bag unimpeded by the film, e.g. through an incorrect closure or a significant hole in the bag. An unimpeded air flow into the bag is what must absolutely be avoided.

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28. When the desired period of protection is one year, would it be possible to reduce the percentage of the VCI masterbatch to achieve this?

A. It is plausible to assume that it would be possible to initiate a development program that might determine the absolute minimum amount of VCI masterbatch for a specific period of protection. The program would be complicated, however, by also having to consider the conditions under which the film would be expected to perform (temperatures, humidity, etc.). It would seem more practical to simply reduce the gauge of the film to achieve a goal of using the absolute minimum amount of VCI for an application.

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29. Are there any examples where plain polyethylene film can be combined with CAPRUST film to provide better overall protection from corrosion?

A. There are applications where plain and CAPRUST film used together in a package provide better protection of packaged parts.
Example 1 : Parts Against Wood or Cardboard.
A row of parts placed on a wood pallet or placed on the bottom row of parts in a wooden crate must have a barrier of CAPRUST film between wood or cardboard and metal to be protected. Sometimes, if the parts are heavy and the wood or cardboard is particularly damp, the CAPRUST film might not be heavy enough to prevent the acids from the wood or cardboard from being forced up through the CAPRUST film at the contact points or surfaces between the part and the wood or cardboard. The needed additional protection of the part can be obtained by adding a layer of plain film under the CAPRUST film.

Example 2 : CAPRUST Bags as Liners in Wooden Crates.
CAPRUST bags are typically used to line the interiors of wooden crates. Crates can arrive at their destination with a surprisingly large of amount of water in them. The water has entered the crate through the cover of the crate. A layer of heavy plain polyethylene film attached to the inside surface of the cover of crate has been shown to keep inches of water away from the interior of a crate.

Example 3 : Water, Polyethylene and High Heat.
CAPRUST bags were being used as liners in cylindrical heavy plastic containers. Cast iron parts were then placed in the CAPRUST bags, the tops of the bags were folded over to close them and a plastic fitted lid closed off the container. The containers were stacked outdoors. Occasionally the lids of the top row of containers either blew off due to the wind or were not placed on the containers. In the first summer that the CAPRUST bags were used Wellpack was asked to explain why the tops of castings in the top row in the CAPRUST bags in the top row of the container were corroded while the rest of the castings in the bag were not corroded. WELLPACK found that rain from periodic summer showers was collecting in depressions on the tops of the folded cover to close them. When the sun heated, the water also relaxed the polyethylene matrix of the film and substantially increased the moisture transmission rate of the film thereby essentially depositing bulk water on the tops of the top row of the castings and initiating corrosion there. The problem was solved by adding a plain polyethylene bag as an outer liner to the interior of the container.

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30. How is the quality of CAPRUST film determined?

A. As stated in CAPRUST literature, all CAPRUST products for ferrous metal protection must pass IIP which the Indian semi government agency use to qualify, and control the quality of, VCI materials for ferrous metal protection. As a result the test has become the basis for measuring the corrosion inhibiting ability of VCI vapors on ferrous metals in most parts of the world. The physical characteristics of CAPRUST films are tested by the producers of the film.

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31. What method is recommended for packaging small parts?

A. There is a point where the sizes of parts reach a point where it is not realistic to consider packaging them individually or in rows. For example connecting rods are generally considered too small to package individually but large enough to package in rows. Bushings are too small to package in rows and are often wrapped 10 or 15 at a time in a cylindrical form. Items smaller than bushings, e.g. fasteners, fittings, etc., tend to be piled into CAPRUST bags for shipment. In this application there is concern as to whether or not the geometry of the massed items will permit all surfaces to be available to the VCI molecules. Also the items will be in contact with each other. Metal surfaces in direct contact with metal surfaces under pressure can suffer a form of attack called crevasse corrosion. Of course the contact points between the items may shift in the package's transit and this problem may not arise. It has been Wellpack's experience that a field trial rather than a laboratory test is the most valuable test for small item packaging.

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32. Corrugated cardboard sheets are often used to separate one row of parts from another in a package. These sheets will absorb moisture in storage and transit and will induce corrosion on part surfaces in contact with the cardboard. How can this be avoided?

A. Part surfaces should never be allowed to touch corrugated cardboard, paper or wood. A sheet of VCI film or VCI paper should be placed on the cardboard surface and then the parts placed on the VCI material. Furthermore a VCI sheet should be placed on top of a row of parts to prevent the bottoms of the cardboard touching the row of parts immediately below it. Another approach would be to place the cardboard sheet in a flat CAPRUST film bag thereby covering both sides of the cardboard sheet.

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33. What are the differences between monoextruded CAPRUST VCI films and coextruded films where one side only contains a VCI formulation?

A.Caprust is a monoextruded film. Caprust monextruded VCI film are capable of better protection and service life if unexposed to air.

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34. Are there any inhalation or contact risks with CAPRUST films?

A. Test data is available from that shows that there are no inhalation or contact risks with CAPRUST films.

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35.Whether printing can be done on VCI film?

A.Yes printing can be done on to the film.

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36.Can vaccumising cause any effect on the film?

A. Vaccumising doesn’t cause any significants effect on to the film.

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37.Is package highly flammable?

A. No package is not flammable.

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38. Are CAPRUST films cost effective?

A. Yes. Labour saving is possible because of the elimination of oil and the labour cost to apply and remove the same. Please go through the module 'comparison' on our site to study the same.

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39.Can CAPRUST film be recycled from CAPRUST scrap?

A. CAPRUST scrap can be used to produce second grade film. Every new caprust product need to produce virgin polythene with CAPRUST master batch must be added. The CAPRUST master batch from scrap cannot be recovered

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