Water-Based Rust Preventative Concentrate – 275 Gallon Tote (Cortec® VpCI®-377)

Description

VpCI®-377 is a water-based rust preventative concentrate that replaces oil-based rust preventatives indoors. The wide dilution range lets you dial protection length against cost rather than buying three products, and the 275-gallon tote is the bulk size for plants that feed several process tanks or a central mixing station from one supply.

VpCI-377 was designed as a direct replacement for oil-based rust preventatives indoors. Diluted in water and applied by dip or spray, it leaves a transparent, dry, hydrophobic film that most coatings can be applied over without removal, so parts go from storage to paint line or assembly with no cleaning step. Protection runs from about a year at 2 to 5 % to more than two years at 10 to 20 %. In the Cortec Product Consultation Guide it is rated 2 (inside storage) on carbon steel, stainless steel, cast iron, aluminum, galvanized steel, copper, brass and solder; it is not for unsheltered outdoor exposure. A winterized grade with a −22 °F (−30 °C) freeze point is available.

Typical applications

• Castings, tubular parts, finished parts, gears
• Pumps and housings
• Textile and printing equipment
• Structural steel and sintered metals
• Additive to washers and rinse systems
• Bar, tube and roll stock in indoor storage
• Machined parts held between operations or ahead of the paint line
• Engine, gearbox and drivetrain components in indoor storage or domestic shipment
• Indoor parts protection for automotive and heavy-equipment tier suppliers

How to apply VpCI-377

1. Surface preparation. SSPC-SP-1: free of grease, oil, corrosion, dirt, dust and mill scale. Parts that have just come through a washer running a VpCI-41x cleaner are ideal.
2. Dilution. Dilute with deionized water; hard water is acceptable but may reduce protection and longevity. Dilute by mass or by volume with light agitation; no special mixing equipment is needed. Choose the concentration from the table below.

3. Concentration in water	Indoor protection	Surface after drying
   2–5 %	Up to 1 year	Little to no observable residue
   5–10 %	Up to 2 years	Slight tackiness on some surfaces
   10–20 %	May exceed 2 years	Noticeable tackiness on most surfaces

   Protection lengths assume indoor storage and vary with conditions. The current data sheet lists a working range of 0.5 to 20 %.

4. Dip. Charge a clean dip tank with VpCI-377 and water to the target concentration, submerge the part and make sure recesses are wetted, then remove and dry before packaging or further processing.
5. Spray. Once diluted the solution has a viscosity similar to water and runs in almost any spray equipment. Spray until every critical surface is coated.
6. Drying. About 15 to 30 minutes at 70 °F and 50 % relative humidity; drips can be reused. Forced air and heat shorten dry time; keep heated drying at or below 175 °F (80 °C) and avoid excessive air, which strips product before the film forms. Dry completely before packaging.
7. Recoat or paint. The dry film is stable to 350 °F and most coatings can be applied over it without removal.
8. Removal. Not normally required. When it is, rinse with water and follow with a VpCI-41x cleaner/degreaser (VpCI-414, 416 or 418LM) to prevent flash rust.
9. Storage and shelf life. 24 months in the original sealed container.

Checking concentration

Concentration (% by volume) = 1.64 × Brix − 0.13 for VpCI-377 in DI water, valid across Cortec’s 0 to 30 % chart. Target readings are about 1.3 °Brix at 2 %, 3.1 at 5 %, 6.2 at 10 % and 12.3 at 20 %. The concentrate has a pH of 7.5 to 9.5, and the current data sheet requires the working solution to stay above pH 8 to remain effective; Cortec’s DI-water chart shows pH moving only about one unit across 0 to 30 %, so use the refractometer as the concentration control and pH as the bath-health check. Field water hardness, cleaner carry-over and oil shift refractometer readings, so build a site-specific reference chart with your own process water. See the refractometer and pH charts for every Cortec product.

Where it fits in the Cortec line

VpCI-377 is the workhorse concentrate of Cortec’s water-based rust preventatives. VpCI-379 is the choice when the part will definitely be painted; BioCorr is the ready-to-use biobased option rated for two years indoors; VpCI-316 is the yellow-metal specialist; EcoCorr is a clear dry-film sibling. For sheltered or outdoor exposure move to the oil-based VpCI-369 or VpCI-329D. To skip the mixing station, VpCI-377 D is the same chemistry pre-diluted, and EcoAir VpCI-377 puts it in a non-flammable compressed-air can for touch-up. VpCI-377 also runs as a rinse-stage additive in Build-All and Magido aqueous parts washers. Browse the full Cortec VpCI line.

Field notes

A Pennsylvania locomotive-engine producer ships engines worldwide and stores them outdoors up to two years. VpCI-377 at 20% in the cooling water is cycled through, drained and recaptured, and the recaptured solution is tested for concentration and reused; the program had run almost nine years as of 2019. (Cortec Case History #622)

An Indiana automotive-electrical plant had parts rusting before they left the building. Its replacement three-stage wash runs 5% VpCI-414 with 0.4% defoamer, a water rinse, then 10% VpCI-377 as the final stage; three months of testing showed no corrosion and the process was approved. (Cortec Case History #095)

An Indiana locomotive-engine plant had test water leaving new cooling systems rusting in outdoor storage between build stages, and the residual water had to be freeze-proof. A mix of 20% VpCI-379, 20% glycol and 60% water is circulated, captured, tested and reused; VpCI-379 has been in the company specification since 1999. (Cortec Case History #623)

Specifications

Protection	Up to 24 months indoors
Dilution	Wide range, 0.5–20% with water
Film	Dry, clear, hydrophobic; stable to 350°F
Important	Solution pH must remain above 8 to be effective
Chemistry	Nitrite and phosphate ester-free, non-flammable, very stable in hard water
Removal	Does not need removal; if required use conventional alkaline cleaners such as the VpCI-410 series
Appearance	Clear dark brown or black liquid (Winterized grade: clear amber)
Non-volatile content	40–47%
pH (concentrate)	7.5–9.5
Density	8.7–9.2 lb/gal
Surface preparation	SSPC-SP-1
Application	Dip or spray; dilute with deionized water
Protection by concentration	2–5% up to 1 year; 5–10% up to 2 years; 10–20% may exceed 2 years (indoor)
Dry time	15–30 minutes at 70 °F, 50% RH; heated drying not above 175 °F (80 °C)
Concentration check	Vol % = 1.64 × °Brix − 0.13 (DI water)
Test	Passes ASTM D4627 iron chip corrosion test at 2% by weight
Paintable	Most coatings can be applied over the dry film without removal
Metals	Carbon steel, stainless steel, cast iron, aluminum, galvanized steel, copper, brass, solder
Consultation guide rating	2 – inside storage
Winterized version	VpCI-377 Winterized: freeze point −22 °F (−30 °C), pH 7.8–8.9, 8.8–9.2 lb/gal
Storage	Sealed, in a heated warehouse to avoid freezing (Winterized grade tolerates cold storage)
Shelf life	24 months
Size	275 Gallon Tote
Shipping weight	2570 lb (1170 kg)
Availability	In stock
Cortec product number	12003660

Solvent Recycling Systems is an authorized Cortec® distributor. See the full Cortec VpCI line, browse the VpCI product selection guide, or contact us for volume pricing and lead times.