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Stain and Paint Defined
• Staining is sometimes referred as stain or paint
• Two different uses
• Careful to be specific so no errors
Prime and Paint
• Oil and water based primers for WRC
• Priming seals and prepares
• Film forming, less deep penetrating
• Always opaque
• Lasts longer than stain
Wood Stain
• Not primed first
• Like a paint but different
• Penetrates
• Protects
• Provides color
• Translucent and opaque
• Enhances the beauty
Stain Type Finish Characteristics
SolventProvide a means for the pigment and binder to be applied to a surface
BinderLiterally ‘bind’ the pigment together, and provide paint film integrity and adhesion
AdditivesLow volume ingredients that provide specific paint properties
PigmentsProvide color and hiding properties, and some are used to add body to the paint while keeping manufacturing costs low
Ingredients of Stain
Pigments are used in stain to give an aesthetic beauty to wood as well as protect the wood from the harmful effects of the sun.
Stain Pigments
Acrylic/oil, 100% Acrylic, Hybrid, Alkyd/Linseed oil, and Waterborne Modified Alkyd are some of the different binders used in stains.
These binders are used in stain to help the stain penetrate deep into the wood, seal it, and give it durability.
Binders
FINISHES CAN BE CLASSIFIED BY THEIR VEHICLES OR BINDERS
• Oil Base
• Solvent base (borne)
• Water Base (borne)
• Emulsion
• Oil
• Alkyd
• Varnish
• Acrylic / Oil
• Polyurethane Acrylic / Oil
Stain Type Finish Characteristics
Water
Water based (Acrylic/ Oil)
Advantages Disadvantages
Better UV resistance than oil Shorter working time
Fast drying Attention to application detail required
Soap and water clean up
Advantages Disadvantages
Longer working time Fade faster than water based products
Easier application More susceptible to mold/mildew than water based productsHard to clean up – Slow drying
Oil based (Solvent Blend)
Solvent Types
Additives – low volume ingredients that aid in manufacturing, and add specific characteristics to the stain
Paraffin wax – adds extra scuff protection & water beading
Mildewcides – prevent mildew from growing
Wood fibers absorb and lose moisture, causing uneven stresses between early and late wood; this causes cracking, cupping, splitting, etc.
Prolonged high moisture content provides excellent environment for moss, mildew and fungus growth
Wood goes through wet/dry cycles
Ideally, vertical wood surfaces should be properly prepared and finished within 3-5 weeks of installation completion
Ideally, horizontal wood surfaces should be properly prepared and finished within 2-4 weeks of installation completion
Finishing all six sides of all exterior lumber is hugely advantageous for providing optimum wood protection from the weather elements
Illustrations of Excessive Weather Exposures
The Nature Of Wood
• Cellulosic fibers- Lignin holds fibers together
• Extractives- Tannins give wood its color
• Water
• Pressure-treated lumber- CCA or ACQ- High moisture content- Mill Glaze
• Cedar-Red Cedar-Redwood- High extractive content- Mill glaze- Cedar is naturally oily
• Tropical Hardwood- Hard- Dense- Oily
Excess Moisture Content –When wood like pressure treated CCA (Chromated Copper Arsenate) or ACQ (Alkaline Copper Quaternary) are delivered to the job site it has a moisture content that is in excess of 40%.
Rapid drying can cause undo stress to the wood fibers that can lead to cracking, warping and cupping etc...
New Wood Can Present Several Problems
The Nature of Wood
New Wood Can Present Several ProblemsMill Glaze – is a term used by the coating industry to define what occurs on
smooth flat grained wood during the milling (wood planer) process.
● Natural oils come to the surface with machining heat
● The wood pores are shut and the finish will not penetrate properly
New Wood Can Present Several Problems
Extractive Content - All wood contains water soluble chemical extractives which are deposited in wood cells as a tree grows.
● Aesthetic problems
● Wet/dry cycles increase extractive bleeding and nail staining
Nail Staining –not always rust from the nail
Extractive Staining
Weathering of New Wood: The Negatives
Ultraviolet light radiation “burns” the wood
● Loosening the wood fibers
- Color is lost and the wood turns gray
● Erodes the wood surface
־ Opens up the wood grain
- Occurs faster in the early wood than in late wood creating a washboard effect
- Wood retains more moisture, promotinggrowth of moss, mildew and fungus
Excess moisture leaves the wood so oils can penetrate
Grain opens up so oils are absorbed more deeply
Extractives are washed away evenly so that appearance is greatly improved
Weathering of New Wood: The Positives“Short-term” weathering of new wood can minimize these problems. Finishes will look better and protect the wood longer.
Illustrations of Aged and/or Previously Finished & Weathered Exterior Wood Surfaces(Refinish or Restoration Required)
Why Stain?
A properly applied finish protects against● Wood destroying fungus- Brown Rot- Dry Rot- White Rot ● Wood- Mildew- Sap Stain● Mold● Algae
Optimum conditions for fungus growthTemperature
● 75-85ºF
Moisture Content● <20% no activity● 20-30% activity increases● >30% encourages fungus growth
Dry Rot
Wood Mildew Infestation
Various illustrations of performing proper surface preparation of all exterior wood surfaces, insuring that surfaces are Clean & Porous (surface absorbency) before applying any type of a finishing material.
Surface Preparation Methods
Factory Pre-Stain Applications
• Controlled application conditions
• Controlled substrate
• Stained or finished 6 sides
• Consistency – machine applied
• Low cost effective
• Year round install and done!
Factory Pre-Stain Applications
• Finish paint warranties
– 15 or 25 years on primed
• Certified Applicators
• Machine Coaters in all regions
• Western Red Cedar Lumber Association (WRCLA)
- “How to Specify Western Red Cedar” Brochure Link:
http://www.realcedar.com/wp-content/uploads/2015/03/76370_HowToSpecifyCedar_text_english_2015.pdf
- “How to Finish Western Red Cedar” Brochure Link:
http://www.realcedar.com/wp-content/uploads/2013/12/HowToFinish_english.pdf
- “Growth Properties and Uses of Western Red Cedar” Brochure Link:
http://www.realcedar.com/wp-content/uploads/2013/12/Growth-Properties_2013.pdf
Resource References #1
• Western Red Cedar Lumber Association (WRCLA)
- “Western Red Cedar Quick-Facts” Brochure Link:
http://www.realcedar.com/wp-content/uploads/2013/06/WRC-Quick-Facts.pdf
• Paint Quality Institute (PQI)
- “Difference Between Paint and Stain” Article Link:
http://www.paintquality.com/en/advice-and-tips/faq/exterior/difference-between-paint-and-stain
Resource References #2
• Journal of Architectural Coatings (Design+Durability Publication)
- “What Works Well With Wood” Article Link:
http://www.durabilityanddesign.com/archive/?fuseaction=view&articleid=3384
• U.S. Forest Products Laboratory (USFPL)
- “Durability of Paint or Solid-Color Stain Applied to Pre-Weathered Wood”
Publication Link:
http://www.fpl.fs.fed.us/documnts/pdf1993/willi93b.pdf
Resource References #3
• U.S. Forest Products Laboratory (USFPL)
- “Solid-Color Stains on Western Red Cedar and Redwood Siding”
Finish Line Publication Link:
http://www.fpl.fs.fed.us/documnts/finlines/finishline_mknaebe_2013_010.pdf
- “Paint, Stain, Varnish, or Preservative ?” Finish Line Publication Link:
http://www.fpl.fs.fed.us/documnts/finlines/finishline_mknaebe_2013_014.pdf
Resource References #4
• Cedar Shake & Shingle Bureau
- Western Red Cedar Sidewall Finishes / Coatings Options Brochure Link:
http://www.cedarbureau.org/cms-assets/documents/4902-639103.finishes-coatings-web.pdf
Resource References #5