Exterior Finishes (also known as Coatings)
There are a variety of paints, stains, and preservative treatments available for Certi-label™ Western Cedar sidewall products. Certi-label™ sidewall products are available pre-finished, (pre-primed or pre-stained) and natural (unfinished).
Please note: A detailed product finishing discussion is beyond the scope of this manual; however, a brief overview is presented below. It is critical to read the instructions on the finish product’s container as well as follow the finish manufacturer’s directions. All areas of the world present unique painting/staining challenges. Some of the topics you should discuss with your sidewall product manufacturer, finish manufacturer, and professional contractor include the following:
- Product coverage
- Surface preparation
- Qualified finish contractors in your area
- Certi-label™ Western Cedar moisture content level recommended for your specific locale
- Appropriateness of finish for Certi-label™ Western Cedar sidewall products
- Drying color versus sample chip color
- Material Safety Data Sheet
- Mildew resistance
- UV resistance and water repellency
- Exterior/Interior finish usage
- Depth of finish penetration
- Application method, including how to cover all sides of product, mixing/stirring (to prevent lap marks), temperature, brush versus spraying tools, and recommended proper clean up and disposal of all tools, brushes and rags. Talk to your finish manufacturer if you have questions about back-priming instructions for your particular project.
- Price. Do not be fooled by a low price. Better quality brands tend to be more expensive. A cheap finish will usually cost more in the long run through quicker weathering, poorer coverage and less pigment. Use only the highest quality products from your finish manufacturer. Quality finish manufacturers have technical help lines you can call (some are toll-free). Advice is also available via the Internet.
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The CSSB recognizes these general types of finishes:
Transparent finishes (penetrating oil-based): clear, allow natural grain to show through, may also include paintable water repellant preservatives. Such treatment can possibly, depending upon the product, inhibit mildew growth as well as rapid change in color due to weathering.
Semi-transparent and semi-solid stains (penetrating oil-based): have some pigment, but allow some wood grain to show.
Paint or solid stain: provide opaque coverage, allowing little to no wood grain to show.
Certi-label™ Western Cedar Sidewall Finishing Systems: Preferred Paint System
Step 1: Factory or field applied oil-based, stain-blocking primer on all surfaces.
Step 2: Field-applied top coat of highest quality 100% acrylic latex paint. This type of top coat is more flexible and more resistant to blistering and cracking. The best protection against extractive bleeding is the application of an oil-based, stain-blocking primer before the top coat is applied.
OR
Less Durable Paint System
Step 1: Factory or field applied oil-based, stain-blocking primer on all surfaces.
Step 2: Field-applied oil-based or alkyd top coat.
CSSB member manufacturers do supply factory-primed products. These products are usually more cost-effective than on-site priming.
Stains
Use oil-based stains only. CSSB member manufacturers can factory-apply a coat of semitransparent or semi-solid oil-based stain. This process is usually more cost-effective than on-site staining. Further enhancing the natural durability of Certi-label™ Western Cedar shingles and shakes, some CSSB members offer pass-through finish warranties on their factory finished sidewall shingles and shakes. These can be further enhanced by application of a final, field-applied top coat. Contact participating CSSB members for details.
To Accelerate the Weathering Process
To hasten the weathering process, apply a bleaching oil finish.
How Soon to Finish
Generally finish products immediately after installation providing that the moisture content is appropriate for both the finish product being used and your locale. If the finish is not applied promptly, adhesion will be compromised (unless additional surface preparation is undertaken).
If you have installed a natural product (unfinished), apply your finish before rain and other moisture are absorbed. Ensure that you account for high humidity concerns.
If you are using a pre-finished product (where finish is applied at the manufacturing plant), ensure that the product is thoroughly dried before applying a top finish coat.
In all instances drying time varies from region to region. Excessive moisture will limit finish adhesion. Check with your professional contractor, finish manufacturer and/or sidewall product manufacturer for assistance.
Surface Cleaning
There are products that claim to be effective for removing dirt, airborne pollution marks, mildew and prior finishes. If you clean the surface prior to finishing, ensure that it is allowed to dry to the finish manufacturer's recommended moisture content level before applying a new finish. Contact your finish manufacturer for more details.
Extractive Bleeding
Extractive bleeding is characterized by the tannins in the wood being dissolved in moisture and migrating to the surface of the product. Rain will sometimes wash these stains away; however if left to weather, the sun can cause polymerization, thus requiring the addition of a tannin blocker and new top coat of finish (ensure proper surface preparation before applying new top coat) once the moisture problem has been solved. Compounds containing oxalic acid appear to be the most effective at removing extractive bleeding stains: ensure you use proper safety precautions and follow the oxalic acid compound manufacturer’s application directions.
Extractive bleeding does not signify failure of the applied finish, but instead is found in applications where a source of moisture is present. Extractive bleeding is not a manufacturing defect nor is it a finish defect; it is a natural phenomenon that occurs in applications. Tannin blocking products help, however, the CSSB does not provide any finish warranty. Check with your sidewall product manufacturer, finish manufacturer, and professional contractor for more assistance.
The CSSB does not warrant this information or instruction regarding finishes. If you see an attractive job that has endured in your locale, inquire about the type of finish used. Once Certi-label™ Western Cedar shingles and shakes are pressure-impregnated treated you must contact the treatment company to determine if a finish, such as paint or stain, is allowable. If there is any confusion whatsoever it is highly recommended that you contact both your sidewall product manufacturer and the finish manufacturer. |
