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Woodworking Math

Spar urethane

Varathane Outdoor Water Based Spar Urethane

The figures Rust-Oleum (Varathane) prints for Varathane Outdoor Water Based Spar Urethane on its own data sheet, at the conditions it names. Where the sheet doesn't give a figure, this page says so rather than borrow one from another product.

Dry to the touch
30 min
Recoat
2 h
Ready for use
24 h (light use)
Full cure
Not on the sheet we read
Coverage
225–350 sq ft per gallon
Thinning
Not on the sheet we read
VOC
Under 275 g/L (2.30 lb/gal)
Conditions
70–80 °F, 50 % RH; apply at 55–90 °F, RH under 85 %
Indoors or out
Exterior
Food contact
The sheet we read makes no food-contact statement

One source: Rust-Oleum (Varathane), the maker of that product

From the sheet: Brushing figures (the sheet also gives an aerosol); for outdoor projects, with UV protection.

Against its kind

Varathane Outdoor Water Based Spar Urethane is one of the products in outdoor clear finishes; here is that kind across every maker we have read.

Outdoor clear finishes: recoat across makers

4 h

span 2–8 h

Median of 3 sources

Outdoor clear finishes: coverage across makers

570 sq ft/gal

span 380–760 sq ft/gal, per coat

Median of 3 sources

Related

Work it out for your project

Sources

  1. Rust-Oleum (Varathane), Outdoor Water Based Spar Urethane technical data VAR-33 (GDH-465), read 2026-11-08.

How the tags work: How we source every number.