Water-Based Non-Tacky Temporary Coating – 55 Gallon Drum (Cortec® VpCI®-391)

Description

VpCI®-391 is a water-based temporary coating that dries hazy and genuinely non-tacky, so parts do not pick up shop dirt. Cortec states it keeps surfaces corrosion-free before welding without hurting weld geometry or mechanical properties. The 55-gallon drum is the size for a dip tank or an airless spray station at the end of a machining or fabrication line.

VpCI-391 is the coating Cortec puts forward when an OEM is tired of scraping cosmoline-type preservatives off supplier parts. It gives medium- to long-term protection indoors and outdoors, does not need to be removed before the part is used, and can be welded through, which eliminates the weld-prep cleaning step. When it must come off, hot water or an alkaline cleaner does it. In the Cortec Product Consultation Guide it is rated 4 (outside, uncovered storage) on carbon steel, stainless steel, cast iron, aluminum, galvanized steel, copper, brass and solder. At 0.4 lb/gal VOC it sits well under the 1 lb/gal Cortec quotes for its water-based coatings against more than 3 lb/gal for solvent-borne ones, and it is available in colors.

Typical applications

• Harsh, outdoor, unsheltered applications
• Weld joint protection
• Multi-metal protection
• Equipment preservation and preventative maintenance
• Transit protection
• Machined surfaces on valves, pumps, motors and gearboxes awaiting shipment
• Replacement for cosmoline-type supplier coatings that would otherwise be cleaned off before assembly or welding
• Unpainted areas on finished equipment

How to apply VpCI-391

1. Surface preparation. The substrate must be free of grease, oil, dirt, fingerprints, drawing compounds, rust inhibitors and anything else that would affect adhesion. Cortec recommends VpCI-440 or a similar phosphatizing pretreatment on production lines, and a minimum of NACE No. 3 / SSPC-SP6 commercial blast on structural steel. No wash primer is needed on aluminum or galvanized steel for this product.
2. Mixing and dilution. Power-agitate to a uniform consistency with a squirrel-cage or drill mixer. VpCI-391 may be thinned with water up to 10 % by volume to adjust viscosity; ask Cortec or us before going further.
3. Conditions. Apply between 45 and 90 °F (7 to 32 °C) with the surface at least 5 °F (2 °C) above the dew point.
4. Equipment. Spray, roll, brush or dip. HVLP or conventional spray: 0.009 to 0.021 in tip, 45 to 55 psi air and 10 psi fluid, 3/8 in ID fluid hose no longer than 50 ft, dual-regulated pot at gun height. Airless or air-assisted airless: 0.015 to 0.035 in tip, 1,800 to 2,500 psi, 3/8 in ID hose (a 1/4 in whip is fine) no longer than 100 ft.
5. Film build. The data sheet recommends 2 to 3 mils (50 to 75 µm) dry; the current data sheet gives 4.9 to 7.3 mils wet for that film. Theoretical coverage is 658 sq ft per gallon at 1.0 mil DFT.
6. Drying. Dry to touch in 30 to 60 minutes and dry to handle in 1 to 2 hours at ambient conditions; force-dry 15 to 20 minutes at 150 °F (65 °C) if needed. Full cure takes 3 to 7 days. No recoat is specified.
7. Handling and welding. The dry film is non-tacky, so parts can be handled, stacked and shipped without picking up dirt, and welded without stripping the weld prep.
8. Cleanup. Clean tools with water while the coating is wet; once dry use butyl cellosolve or MIBK, following the solvent manufacturer’s safety directions.
9. Removal. For a film at the recommended 2 to 3 mil DFT: spray the surface generously with VpCI-414 at 60 % in water (the coating-removal strength on the VpCI-414 data sheet), let it sit 10 to 15 minutes, then power-wash at 115 to 160 °F (46 to 71 °C) and 50 to 300 psi. Repeat until the coating is gone. The brochure also lists plain hot water or an alkaline cleaner as removal methods for VpCI-391.
10. Storage. Keep the container sealed, do not let it freeze, and do not store above 100 °F (38 °C).
11. See the Cortec coatings application guides and comparison table for the shared spray, prep and storage instructions across the Cortec coating range.

Where it fits in the Cortec line

VpCI-391 is one of Cortec’s four top-selling temporary coatings with VpCI-389, VpCI-368 and VpCI-369. Pick 391 over 389 when the part will be handled, machined or welded before the coating comes off; the 389 film is waxy and slightly tacky, the 391 film dry and hazy. If the coating is meant to stay on permanently, the weldable water-based topcoat is VpCI-386. The remover is VpCI-414. For rusted steel, clean first with VpCI-422 or VpCI-426 rust remover, or convert the rust in place with CorrVerter. Browse the full Cortec VpCI line.

Field notes

A grain and fertilizer terminal operator on the Ohio River found loaders moving deicing salt and fertilizer looked ten years old after one year and were replaced every 2 to 3 years. Once a year each loader is power-washed with an alkaline cleaner to neutralize the salts, dried and oversprayed with VpCI-391 everywhere except the glass. The program has run a decade with no permits needed for the low-VOC coating. (Cortec Case History #735)

A Southeastern U.S. construction-equipment maker had loaders and skid steers sitting outside 6 to 12 months around dealer shipment, and the old oily rust preventive stayed sticky, collected dirt and could wash off. After testing VpCI-391 on fiberglass cabs and paint from about 2017, it goes on unpainted parts, bolt heads, hydraulic boxes, rims and tubing; no appearance complaints, and most dealers leave it on. (Cortec Case History #776)

A U.S. Air Force base in Japan preserved about 20 million dollars’ worth of airfield damage-repair vehicles parked in an open field: VpCI-415 pressure wash, VpCI-369 D on hinges, ElectriCorr VpCI-239 on electricals, VpCI-105 and VpCI-111 emitters in cabs and fuse boxes, VpCI-391 in engine compartments, VpCI-386 CMA over the paint and VpCI-705 in the fuel. Other Pacific bases asked to copy it. (Cortec Case History #557)

Specifications

Salt spray (ASTM B117)	250 hours
Humidity (ASTM D1748)	1,400 hours
VOC (ASTM D3960)	0.4 lbs/gal (48 g/L)
Coverage	658 sq.ft/gal @ 1.0 mil DFT
Recommended DFT	2–3 mils (50–75 µm)
Film	Hazy, dry, non-tacky
Removal	Use a VpCI-41x series alkaline cleaner/degreaser
Type	Water-based removable (temporary) coating
Volume solids	41%
Recommended WFT	4.9–7.3 mils (124–185 µm) for 2–3 mils DFT
Viscosity	1,000–7,000 cP
Weight per gallon	8.4 lb (1.00 kg/L)
Flash point	212 °F (100 °C)
Dilution	Water, up to 10% by volume to adjust viscosity
Dry to touch / dry to handle	30–60 min / 1–2 hr
Force dry	15–20 min at 150 °F (65 °C)
Full cure	3–7 days
Weldable	Can be welded without removing the coating
Colors	Available in different colors
Surface preparation	Clean and contaminant-free; NACE No. 3 / SSPC-SP6 on structural steel
Application temperature	45–90 °F (7–32 °C), surface 5 °F above dew point
Metals	Carbon steel, stainless steel, cast iron, aluminum, galvanized steel, copper, brass, solder
Consultation guide rating	4 – outside, uncovered storage
Removal procedure	VpCI-414 at 60% for coating removal, let stand 10–15 min, then power wash at 50–300 psi and 115–160 °F (46–71 °C); or hot water
Storage	Original packaging, indoors, out of direct sunlight, 40–100 °F (4–38 °C)
Shelf life	2 years
Size	55 Gallon Drum
Shipping weight	503 lb (228 kg)
Availability	In stock
Cortec product number	12302539

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.