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Series 91-H2O | Hydro-Zinc

Generic Type Aromatic Urethane, Zinc-Rich
Common Usage A two-component, moisture-cured, zinc-rich primer for the interior and exterior of steel potable water tanks. Provides outstanding long-term corrosion resistance when used as a primer in conjunction with other Tnemec potable water tank coatings. It cures quickly and can be topcoated the same day at surface temperatures down to 35°F. Series 91-H2O has no maximum recoat time, making it ideally suited as a primer for both sides of plate steel surfaces in water tank fabrication shops. Application methods include “dry-fall” under certain conditions (see Application). Note: When used in conjunction with cathodic protection, anodes or impressed current systems should not provide current demand more negative than –1.05 volts relative to a copper–copper sulfate reference electrode half-cell.
Colors Greenish-gray
Topcoats Please refer to Tnemec's Systems Guide for Water Storage Tanks for specific systems and additional information.
Interior: Series 20, FC20, 22, FC22, L140, L140F, N140, N140F, V140, V140F, 406.
Exterior: Series 27, 27WB, 66, L69, L69F, N69, N69F, V69, V69F, 73, 115, L140, L140F, N140, N140F, V140, V140F, 161, 1028, 1029, 1074, 1074U, 1075, 1075U. Note: Certain topcoat colors may not provide one-coat hiding depending on method of application. Contact your Tnemec representative. Note: Series 91-H2O must be exterior exposed for three days prior to topcoating with Series 1028 or 1029. Note: Series 91-H2O must be exterior exposed for one day prior to topcoating with Series 27WB.
Volume Solids 63.0 ± 2.0% (mixed)
Recommended DFT 2.5 to 3.5 mils (65 to 90 microns)
Curing Time Without 44-710
Temperature †To HandleTo Recoat
75°F (24°C)1 hour4 hours
65°F (18°C)1 1/2 hours5 hours
55°F (11°C)2 hours6 hours
45°F (7°C)2 1/2 hours7 hours
35°F (2°C)3 hours8 hours
† 50% relative humidity. Note: Refer to product listings on for specific potable water return to service information. Curing time will vary with surface temperature, humidity and film thickness. Ventilation: When used as a tank lining or in enclosed areas, provide adequate ventilation during application and cure. Reference ventilation guidelines contained in the latest edition of AWWA D 102.
Note: For faster curing, low humidity and low-temperature applications, add No. 44-710 Urethane Accelerator (see separate product data sheet). Note: For cure times to immersion service, reference the specified Tnemec interior topcoat product data sheet.
Volatile Organic Compounds Unthinned: 2.65 lbs/gallon (318 grams/litre)
Thinned 2.5%: 2.76 lbs/gallon (331 grams/litre)
Thinned 10%: 3.07 lbs/gallon (368 grams/litre)
HAPS Unthinned: 5.05 lbs/gal solids
Thinned 2.5%: 5.33 lbs/gal solids (No. 2 Thinner); 5.06 lbs/gal solids (No. 3 Thinner)
Thinned 10%: 6.19 lbs/gal solids (No. 2 Thinner); 5.09 lbs/gal solids (No. 3 Thinner)
Theoretical Coverage 1,011 mil sq ft/gal (24.8 m²/L at 25 microns). See APPLICATION for coverage rates.
Number of Components Two: Part A and Part B
Chemical Name(required)
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Note: Not Recommended (NR), Not Tested (NT), Please Call (PC)


The chemical resistance data listed on this website should only be used for general reference purposes. Substrates, temperatures, chemical combinations, and other variables can affect the performance of a coating in chemical exposure. Please contact your local Tnemec Coatings Consultant to finalize the most appropriate system for your project.

Click the following button to download a PDF of the list of chemicals below.

*Results are NOT suitable for direct or indirect food contact. Intended use exposure results relate to product's performance and substrate protection capabilities only.

Recommended Use
Chemical <90°F (32°C) 90-120°F
*Results are NOT suitable for direct or indirect food contact. Intended use exposure results relate to product's performance and substrate protection capabilities only.
  • Color cards, swatches and fan decks are offered at no charge, by request , for more accurate color selection. Expert custom color matching is also available by contacting your Tnemec Coatings Consultant .
  • Deeptone colors may be more expensive than lighter colors. Please contact your Tnemec Coatings Consultant to verify product/color availability and pricing.

Products Available In Greenish-Gray 

Greenish-Gray| rgb 121,121,109
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These digital colors should not be used to finalize your color selection. Please read our disclaimer . Use the color swatch tool on the left to request official color swatches.

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The products listed below are not exact equivalents. They are only products that you may consider as alternatives in a general sense. Substrate type, condition, temperatures, surface preparation, primer/topcoat selection and intended use are just a few factors that will affect product selection. Please contact your local Tnemec Coatings Consultant for product recommendations.

This ProductAromatic Urethane, Zinc-Rich
Series 94-H2O | Hydro-Zinc Aromatic Urethane, Zinc-Rich
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Volume Solids Rec. DFT V.O.C. # of Components
62.0 ± 2.0% (mixed) 2.5 to 3.5 mils (65 to 90 microns) per coat. Unthinned: 0.81 lbs/gallon (97 grams/litre)
Thinned 15% (No. 49 Thinner): 0.81 lbs/gallon (97 grams/litre)
Thinned 10% (No. 3 Thinner): 1.62 lbs/gallon (194 grams/litre)