Exterior 450 Water Based Topcoat

Exterior 450 Topcoat a clear-drying finish suitable for vertical exterior surfaces, such as fences, patio furniture, garage doors, entrance doors and interior windows. It is not recommended as a deck finish. Exterior 450 is fortified with UV absorbers to stabilize the finish and built-in mildewcide to retard mold and mildew growth. It performs well as a clear coat or as an optional topcoat over General Finishes Milk Paint. 

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General Finishes Satin Exterior 450 Water Based Topcoat, Gallon

Instructions

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.

Step 2: How To Apply General Finishes Exterior 450 Topcoat

General Finishes Exterior 450 Topcoat Application Steps

  1. Stir topcoat to reincorporate solids that have settled to the bottom of the can before and throughout the application process.
  2. If desired, thin with up to 15% distilled water or General Finishes Extender. Start by adding 5% in increments until you reach the desired consistency. GF Extender will improve flow and leveling and increase open time, which is helpful in dry climates. 
  3. Apply 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.
  4. Dry 2+ hours between coats in ideal conditions: 70°F/20°C; 50-70% 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.
  5. Finish sand between coats with a fine-grade (220-320) foam sanding pad to improve smoothness and adhesion.
  6. Remove dust with a vacuum, compressed air, an oil-free tack cloth or a water-dampened rag.

Cure Time
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.

Cleanup of Water Based Products

Application tools and materials containing water-based products can be cleaned with soap and water or GF Brush & Gun Cleaner immediately after use.

Product Spills
Spills may be able to be removed from fabric and carpet if cleaned immediately with soap and water.

Storage of Water Based Products

Life of Product
Water-based products do not last forever, even when unopened. General Finishes products are best used within 1 year of the manufacture date listed on the bottom of the can. The life of the product may be extended with proper care and storage.

Settling
Gravity can cause some solids to settle on the bottom of the can and slight separation on the top. This is normal. If working with older paint, use paint mixing attachment on a drill. If the solids dissolve and clumps smooth out after mixing from the bottom, the product is in good condition for use.

Storage Tips
See video tutorial: Tips on Storing Leftover Finishes
Water-based finishes crystalize and form a skin due to evaporation when the air-tight seal on a can is broken at first use. The following best practices will increase the life of your product:

  1. Pry open sealed lids with a paint can opener by hooking under the lid's rolled edge. The use of a screwdriver can disfigure the rim and lid, impairing a complete seal. 
  2. Keep lid closed while working. Pour what you will use into a bowl, paper cup, or plate, and close can lid as you work.
  3. Clean the chime of the can thoroughly with a paper towel before closing to create a complete seal. Paint in the chime can be minimized by using a pouring lid, such as Fitsall. Avoid wiping used brushes on the lid.
  4. Pound the lid in place using a rubber mallet to avoid distorting the chime or lid. Dents in the lid from direct contact with a hammer can impair a complete seal. Alternatively, place a flat piece of wood over can lid and firmly pound shut.
  5. Store in moderate temperatures. Avoid temperatures below 50°F/10°C or above 80°F/26°C. Keep from freezing. Frozen and heat-damaged product cannot be revitalized. Temperature-controlled spaces, such as a basement, are ideal for storage. Do not store product in an attic, garage, in direct sunlight, or next to something warm like a water heater or furnace.
  6. Store can upside down to create a liquid seal, minimize evaporation and reduce the chance of crystallization. Decant remaining product from the can before stirring. 
  7. Decant leftovers to a smaller container when the finish is almost used up. Alternative storage containers for water-based products are plastic FIFO bottles or glass bottles. Do not fill metal-lidded containers completely to prevent them from rusting.

The following water-based product mixtures can be stored:

  1. Product thinned with up to 15% General Finishes Extender or General Finishes Accelerator can be stored, with the exception of thinned General Finishes Water Based Wood Stain.
  2. Mixtures involving colors & sheens within the same product line, such as:
    • High Performance Satin + High Performance Gloss
    • Snow White Milk Paint + Coastal Blue Milk Paint
    • Amber Dye Stain + Merlot Dye Stain

The following product mixtures should NOT be stored:

  • Any water based product with thinned tap water; water often contains bacteria that will adversely affect stored paint.
  • Topcoat + Stain or Paint
  • Milk Paint + Chalk Style Paint
  • Water Based Wood Stain + Dye Stain

Furniture Care & Maintenance

Cure First
Allow 21 days for the finish to cure before heavy use or cleaning with commercial products.

Regular Cleaning and Maintenance

  • Remove dust with a water-dampened cloth. Dust can build up over time and may scratch or dull finishes if not removed regularly. 
  • As with all furniture finishes, avoid using furniture polish, cleaners or dusting sprays that contain silicone, alcohol, ammonia and anything acidic. Future finishes or touch-ups may not adhere properly or perform as desired over a contaminated surface. Some contaminants, such as silicone, seep through finish into the wood and often cannot be removed.
  • Clean up water, alcohol and food spills in a timely manner and use placemats & coasters to protect the finish.

Warnings and Warranties

Compatibility: Do not use water-based products with Linseed Oils or Danish Oils.

Limited Warranty
General Finishes products must be tested to your complete satisfaction before using, including compatibility with other manufacturers products. General Finishes will be responsible only for the cost of our products and will not be responsible for any costs such as labor, damage, or replacement costs.

Contamination and Compatibility
Our finishes are engineered as a system and are compatible with each other. General Finishes cannot guarantee an ideal refinish when applying our products on top of or combined with another company's products or over surfaces that have been in contact with waxes, polishes or sprays containing contaminants such as silicone. Test for adherence and aesthetics before beginning. 

Danger: Contents are COMBUSTIBLE. Keep away from heat and open flame. Application materials or other waste soaked with this product may spontaneously catch fire if improperly discarded. Immediately after use, place rags, steel wool or waste in a sealed, water-filled, metal container. Dispose of in accordance with local fire regulations.

CAUTION: Contains ALIPHATIC HYDROCARBONS. VAPOR HARMFUL. Use only with adequate ventilation. DELAYED EFFECTS FROM LONG-TERM OVEREXPOSURE. Contains solvents which can cause permanent brain and nervous system damage. Intentional misuse by deliberately concentrating & inhaling the contents can be harmful or fatal.

Warning
If you scrape, sand, or remove old paint, you may release lead dust. LEAD IS TOXIC. EXPOSURE TO LEAD DUST CAN CAUSE SERIOUS ILLNESS, SUCH AS BRAIN DAMAGE, ESPECIALLY IN CHILDREN. PREGNANT WOMEN SHOULD ALSO AVOID EXPOSURE. Wear a NIOSH-approved respirator to control lead exposure. Clean up carefully with a HEPA vacuum and a wet mop. Before you start, find out how to protect yourself and your family by contacting the National Lead Information Hotline at 1-800-424-LEAD or log onto www.epa.gov/lead.

Do not swallow; first aid: drink water to dilute product. May cause eye and skin irritation; first aid: flush eyes thoroughly with water.

FIRST AID: In case of eye contact, flush thoroughly with large amounts of water for 15 minutes and get medical attention. For skin contact, wash thoroughly with soap and water. In case of respiratory difficulty, provide fresh air and call physician. If swallowed, do not induce vomiting. Get medical attention immediately. 

Warning
This product contains a chemical known to the State Of California to cause cancer and birth defects. Do not swallow; first aid: drink water to dilute product. May cause eye or skin irritation; first aid: flush eyes thoroughly with water.

Specifications

Basic Features
Product Colors Water White in can (dries clear)
Base Type Water
Ambering No
Sheen Flat (10 or less), Satin (25-35), Semi-Gloss (50-60), Gloss (85+)
Interior or Exterior Exterior
Type Urethane/Acrylic Blend
Application
Coats 3 coats
Application Method Brush, Roll, Spray
Brushable Yes
Usable over existing finishes Yes
Sprayable Yes
Spray Tip Sizes HVLP 1.1mm-1.3mm
Dry Time
Dry Time - Touch 30+ min.
Dry Time - Recoat 2+ hr
Dry Time - Light Use 7-10 days
Dry Time - Cure 21 days
Contents
Can Sizes Quarts, Gallons, 5 Gallon pails, 55 Gallon drums
Coverage 150 sq. ft/quart, 600 sq. ft/gal
Technical Data
Viscosity Medium
Viscosity (cPs) 350-450
Weight Solids 31%
VOC <128 g/L
Durability
Durability (Highest, High, Medium, Low) High
Hardness (Koenig #) 30
Wear (Taber #) 95.30 mg loss
Water 5
Chemical 92

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FAQs

Can General Finishes Water Based Top Coats Be Tinted?

All of General Finishes water based topcoats can be tinted to create lightly colored finishes for toning. Toning is the process of adding colorant, either dye or pigment into a top coat and then applying over an entire piece in order to subtly deepen the color.

Some tinting recommendations are:

  • Do not exceed 13 ounces per gallon. Excess amounts of colorant can create surface defects and decrease the viscosity (causing drips, sag, etc.).
  • Tinting a product black only requires about 6 to 8 ounces (based on strength of colorant).
  • Check for colorant compatibly (best to use a zero VOC colorant).
  • Tint off whites with white bases.
  • Enduro-Var top coat cannot be tinted white.
  • GF top coats can also be tinted with General Finishes Dye Stains or Trans Tint Dyes available at many woodworking and paint stores. This produces a transparent tinted finish. Normal addition is usually 2-5% by volume.

GF does not manufacturer colorants. Here are a few sources:

  • Mixol available at Woodcraft
  • Gennex by Benjamin Moore
  • Colortrend 896 or 888, 878

Relevant Videos

I used Exterior 450 over mix of mineral spirits & Trans Tint dye stain and the finish is peeling - how can I fix the peeling?

Most dyes such as Trans Tint can only be mixed with alcohol or water, not mineral spirits. A water-based finish such as Exterior 450 cannot be used in conjunction with mineral spirits, even with an extended dry time. Solvents of any kind do not play well with water-based finishes. Unfortunately, you will have to sand the project down, apply an exterior stain and recoat with Exterior 450. Also, advise your customer that no finish will withstand the sun indefinitely. All exterior finishes need recoating and maintenance over time.

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Should I use Pre-Stain Conditioner Before Staining a Douglas Fir Door to prevent blotching?

Douglas Fir is a difficult wood to stain evenly. A 50|50 mix of your Exterior 450 stain color and Exterior 450 Clear would be a better choice for an exterior conditioner. Blotching may still occur even with this procedure.

After applying the conditioner mix, let it dry 2-3 hours. Allow more time in humid weather. Then a apply the stain color of your choice. Multiple coats will deepen the color.

 

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Which Topcoat Should I Choose?

General Finishes Water Based Topcoats:

  • High Performance
  • Flat Out Flat
  • Enduro-Var
  • Enduro Professional Topcoats (Enduro Clear Poly, Enduro Conversion Varnish, Enduro Water Based Laquer)

General Finishes Oil Based Topcoats

  • Arm-R-Seal Liquid Oil Based Topcoat
  • Gel Satin Topcoat

GENERAL PRACTICE:

  1. Oil based topcoats and Enduro-Var will amber over time.
  2. Water based Flat Out Flat and High Performance top coats dry clear.
  3. Never use any water based topcoat with long oils such as Danish, Tung or Linseed.
  4. Water based top coats clean up with water. OIl based topcoats require mineral spirits for clean up.
  5. Enduro-Var ADHERES WELL only over WATER STAINS, DYE STAINS, and RAW WOOD.
  6. If you use water based topcoats over oil based finishes, make sure that you wait 72 hours between the two products. It is essential to let the oil finish dry longer.
  7. Large/Detailed Surfaces - For more complex projects that have a lot of nooks and crannies or projects with large surface areas such as cabinets, we recommend either ARM-R-SEAL liquid oil based topcoat or any of our water based topcoats.
  8. Enduro Professional Top Coats are thinner and intended to be sprayed
  9. High Performance and Flat Out Flat can also be sprayed. If needed, it can be thinned by adding 10% water or Extender. Large surfaces such as cabinets or tables and complex projects with lots of detail are easier to cover with liquid top coat rather than a Gel top coat.

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