CAUTION: Do NOT use Exterior 450 or any other clear coat, over white or light paints such as GF Milk Paint, or GF White Poly as it may cause yellowing. Any clear coat can become reactive over wood substrates or existing finishes, causing tannin or dye bleed-though regardless of priming. All of GF's white paints do NOT require a topcoat.
NOTE: Exterior 450 Topcoat is not intended for decks. It can be used on tabletops that do not receive direct exposure to sun and rain. As with all fine furniture finishes, wipe up spills in a timely manner to protect the finish.
General Finishes Exterior 450 Topcoat Application Steps
- Stir topcoat to reincorporate solids that have settled to the bottom of the can before and throughout the application process.
- Thin as desired with distilled water; start with 5%, increase up to 10% by volume. Increase open time, if needed, with up to 5% General Finishes Extender if allowed by local regulations. GF Extender will improve flow and leveling and increase open time, which is helpful in dry climates. California Residents: Adding more than 2% of GF Extender will make the product
s non-compliant per SCAQMD Regulations. GF assumes no liability for the improper use of these products.
- Apply 2-3 coats of Exterior 450. More coats will not improve durability.
- Hand application: Apply a liberal amount of product using a synthetic bristle brush, foam brush, pad applicator or roller. Avoid pressure and excessive back-brushing. Brush along the wood grain using smooth, even strokes with light lap marks. Let lap marks dry; they WILL tighten down.
- Spray application: Before spraying, strain topcoat through a fine-mesh filter. Spray wet films at 3-5-mil thickness. HVLP: 1.1mm-1.3mm spray tip, medium air cap. Verify tip sizes with your equipment supplier. See our general guide for spray tip sizes. Keep your gun at a 90° angle, 6-8" from the surface. On large, flat areas, use wet, even patterns 6-8" wide. For narrow surfaces, reduce the fan pattern to 2-3" wide to reduce overspray. Overlap each pass 25% to conceal lines. Wear a full filter respirator (NIOSH/MSHA approved) and work in a ventilated space. Visit this FAQ for more information on spraying techniques.
- Dry 2+ hours between coats in ideal conditions: 70°F/21°C; 50% humidity. Be sure to allow adequate dry time. You can tell if a water-based finish is dry if it forms a powder when lightly sanded with a fine-grade (220-320) foam sanding pad. If in doubt, wait longer. Rushing the dry time can cause "blush," which is clouding in the finish due to moisture trapped between the layers. Increase dry time if:
- Humidity is over 80%
- 3+ coats are applied
- Thick coats are applied
- To accelerate dry time in humid conditions, add General Finishes Accelerator and work in a space with good ventilation and air movement. If you decide to re-coat before the recommended time, test dryness.
- Finish sand between coats with a fine-grade (220-320) foam sanding pad to improve smoothness and adhesion.
- Remove dust with a vacuum, compressed air, an oil-free tack cloth or a water-dampened rag.
Ready for exterior use: Allow 5-6 days before putting your project outdoors. Note, the UV additive in 450 Clear will protect the integrity of the finish, but will not prevent the wood from changing color from sunlight.
Water-based finishes cure and harden for full use after 21 days in ideal conditions. Avoid placing heavy objects on surfaces that have not completely cured. Treat gently, and do not clean with commercial products during the curing period.
NOTE: Exterior 450 is designed to let the water permeate the finish; as it dries, the water releases back out to allow the finish to tighten down again. Temporary cloudiness may occur as the finish dries.
WARNING: We do not recommend Exterior 450 stains or topcoats for exotic woods, ipe, teak or other dense, oily woods.
Warning: Do not use water-based products with Linseed Oils or Danish Oils.