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GLOSS General Finishes Exterior 450 Topcoat 5 GALLONS

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Description

Exterior 450 Topcoat a clear-drying finish suitable for vertical exterior surfaces, such as fences, patio furniture, garage doors and entrance doors. It is not recommended as a deck finish. Exterior 450 is fortified with UV absorbers to stabilize and protect the integrity the finish*, and built-in mildewcides to slow mold and mildew growth. It performs well as a clear coat or as an optional topcoat over darker colors General Finishes Milk Paint. Do not use over light or white paints as yellowing may occur. *The UV additive in 450 Clear will protect the integrity of the film, but will not prevent the wood from changing color from sunlight. 

Step 1: Prep Sanding for General Finishes Exterior 450

All wood projects require preparation sanding. If you skip this critical step, your finish may fail.

Preparation for Raw Wood Projects
See our video: How to Prep Sand Raw Wood

  1. 120-grit sandpaper followed by 150-grit or 220-grit sandpaper. Do not over-sand with fine-grit sandpapers; this will close and seal the wood grain, preventing ideal color absorption. Also, do NOT use steel wool on water-based based finishes; the particles will get trapped in the finish and rust.
  2. Remove dust with a vacuum, compressed air, an oil-free tack cloth or a water-dampened rag.
  3. Let dry completely before applying General Finishes Exterior 450.

New Stained Surface: Do not sand. Apply directly to stained surface. 

Sealed Surface

  1. Scuff clean with a Scoth-Brite™ pad or maroon synthetic steel wool & 50:50 mix of denatured alcohol & water. 
  2. Dry 1-2 hours
  3. Sand lightly with 220-320 grit foam sanding sponge. 
  4. Remove dust.

Step 2: How To Apply General Finishes Exterior 450 Topcoat

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

  1. Watch product overview video here (2:31 minutes)
  2. Work in a well ventilated area.
  3. Stir topcoat to reincorporate solids that have settled to the bottom of the can before and throughout the application process. Do not shake. 
  4. Test for adhesion when applying over an existing finish. 
  5. Thin as desired with distilled water; start with 5%, adding up to 10% by volume. 
  6. Increase open time, if needed, with 10-15% 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 products non-compliant per SCAQMD Regulations. GF assumes no liability for the improper use of these products.    
  7. Apply 2-3 coats of Exterior 450. More coats will not improve durability.Finish sand between coats with a fine-grade (220-320) foam sanding pad to improve smoothness and adhesion. Do not use steel wool.
    • Hand application: Apply a liberal amount of product using a synthetic bristle brush, foam brush, staining pad, 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.
  8. Remove dust with a vacuum, compressed air, an oil-free tack cloth or a water-dampened rag.

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. The UV additive in 450 Clear will protect the integrity of the finish, but will not prevent the wood from changing color from sunlight.

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.

Dry Time

​​​​​​Dry Time Between Coats
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 or 400-grit sandpaper. 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.

Ready for exterior use: Allow to dry 5 days before exposing to the exterior elements. 

Cure Time Before Use
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.

Additional Details

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