|
CDF APPLICATION NOTES
SURFACE PREPARATION
For jobs other than newly completed projects, some preparation of the wood prior to finishing may be needed. This will help insure professional results and allow the finish to hold upmuch longer.
Make sure the surfaces are clean and free of discoloration. Dirt and grime may be removed with a mild solution of all purpose cleaner and water. Tough jobs may require the use of commercial grade products such as Woodpal Weather Wood Restorer which removes damaged wood fibers, dirt, grime and surface mildew, restoring the wood to its natural beauty.
Buildings and decks can also be washed down with a solution of sodium percarbonate such as Bi-O-Kleen Oxygen Bleach. Sodium percarbonate is totally environmentally sould. In water it disassociates into hydrogen peroxide,, soda ash and water. However, don't use it on on-aged redwood, which has a pH of about 4, whereas percarbonate has a pH of 10.5, and will darken the redwood.
Trisodium phospate or TSP is the recommended clean for redwood. As redwood ages the pH becomes more neutral, making older decks and siding material less negatively affected by safe bleaching agents.
Sodium percarbonate generally comes in beaded or granular form. It fully dissolves in water in 2 minutes and the recommended usage rate is typically 6 ounces per gallon. As a rule, the hotter the water, the faster any bleaching agent will work.
When using bleaches, it’s also important to first wet down the surface with a water hose. Scrubbing with a push broom is the recommended way of cleaning wood surfaces with bleaches. Sodium percarbonate takes 10 to 20 minutes to work.
After a good scrubbing, rinse to remove any dead wood fiber and let dry completely. Normal household water pressure of 45-55 psi is adequate. You should not need to “power wash”.
Proper precautions should be taken when rinsing chlorine bleach (toxic and corrosive) or oxalic acid (poison). No special precautions are necessary with sodium percarbonate based products since they are non-toxic and non-poisonous.
Of all the deck and/or wood bleaches, sodium percarbonate is thought by many to be the only environmentally friendly choice. It’s also ideal for bleaching and cleaning any other exterior wood surface, except new redwood! When done correctly, bleaching lightens the color of the wood and helps prevent darkening over time. Sodiumpercarbonate will also help control mildew stains and odors.
Yet another problem often encountered in older structures is wood rot, which can be treated with products specifically formulated for this purpose. In severe cases, rotten spots or components should be removed or replaced. Small voids may be filled with exterior grade wood putty or other filler.
Wood that has been painted or treated with creosote won’t accept CDF penetrating finish. These surfaces must be stripped and the grain opened by sanding or other means. Thankfully, environmentally-friendly paint strippers are available.
[ back to top ]
ADDITIONAL COMMENTS REGARDING LOG CONSTRUCTION
For best results apply Velvit CDF to log consturctions when the timber is well seasoned (dried). Of logs are green (recently cut with high moisture content) some finish contractors feelit is best to apply a protective preservative such as ChemGuard Wood Treatment and then allow the timber to season until the moisture level reaches approximately 20%.
Such treatments help protect the wood from mold, mildew, decay and insect infestation while th elogs are allowed to season for 6 to 9 months. Since the wood preservative do not seal the surface, moisture can escape at a more or less normal rate allowing the logs to day. However, one can often avoid the use of treatments during drying time in regions where the humidity is charactistically low and insect infestation is not a problem, especially when the logs have been debarked.
Velvit CDF should be applied to logs with moisture levels of 15 to 20%. Moisture content can be measured with a moisture meter designed for this purpose. Too much moisture results in poor adhesion of the finish and/or degrade due to checking and shrinkage inherent to the seasoning process.
[ Back to top ]
GENERAL DIRECTIONS
Best results are obtained when all surfaces are clean, dry, unpainted and unsealed. The wood should be completely dry before applying Velvit CDF. Allow two to three days drying time after a rainstorm; begin work a few hours following morning dew.
Ideal temperature should be between 50 and 90ûF. Apply finish in the shade when possible as hot sun can dry finish too quickly. This will reduce penetration and may cause overlap marks.
For most exterior applications, a pigmented finish is preferable. While UV inhibitors are added to Velvit CDF, they protect against graying of the wood but not against degrade due to UV light. Pigmented finishes are best because clear finishes absorb UV light causing the finish to eventually break down. Pigmented finishes reflect UV light and for this reason are more resistant to exposure.
When using pigmented Velvit CDF, try the color first in a small obscure area to sure it is what you want! Shades will vary depending on the natural tones and porosity of the wood. Mix pigmented finishes thoroughly. Stir frequently while applying to keep color uniform.
Apply CDF liberally with brush, roller, shake strainer, stain pad or spray gun. For long lasting protection, the wood cells must be thoroughly saturated with Velvit CDF. The first coat should typically be applied at the rate of 250 sq.ft. per gallon; the second coat at 300 sq.ft. per gallon. Particular attention should be given to joints, end grain, drying cracks and lower portions of windows and doors.
Eliminate overlap marks by breaking larger areas down into smaller sections. Use windows and doors as break points. Work from the wet section to the dry one. Do not allow pigmented CDF to set before applying to the next section without a breaking point. However, there is little need to rush or hurry since CDF remains open or wipeable for a good while following application to smooth surfaces.
[ Back to top ]
NUMBER OF COATS
Two initial coats are recommended. However, the finish can be applied differently depending on whether the surface is primarily vertical or horizontal.
Apply two coats back to back on all vertical surfaces. No need to wait for the first coat to dry. While the first coat is still tacky—between 2 and 4 hours—apply the second coat. This method allows the water repellent and the oils to bond tightly with the wood fibers resulting in greater durability, added protection and enhanced color.
As mentioned above, stopping at natural breaking points, such as windows, corners or doors, will help prevent overlap marks.
[ Back to top ]
DECK APPLICATIONS
The preceding comments referreed mainly to vertical surfaces such as walls. For horizontal surfaces such as decks or porches subject to foot traffic, two methods are commonly suggested by finishing professionals.
The first method suggests allowing the deck or porch to weather for one season. The thinking here is that both treated lumber—as well as some new woods such as oak—don’t allow for deep penetration of the finish. This is due to chemicals used in treated wood and the high level of resins and tannic acid found in new wood.
Those who adhere to this first method believe applying finish too soon after construction is the reason so many decks have peeling problems. Once the wood has weathered a season, apply a generous coat of Velvit CDF. Then, wait one year and apply a second coat. This method results in great longevity of the finish.
The second method is similar, but without weathering. Apply one coat initially to the new deck, wait one year, and then appy the second coat.
The reasoning behind waiting a year between coats is simple. If both are applied initially, foot traffic will “walk one coat off” the surface, leaving a wear pattern. Allowing the first coat to set in a year avoids this effect and results in a longer lasting, more durable surface.
[ Back to top ]
MAINTENANCE
To maintain the finish and resulting protection, apply touch up as needed when weathering or abrasions occur. On some new wood, excess moisture from inside the wood may be released over a period of one to two years.
Once stable, another coat can be applied, which will result in a great deal of added protection for many years to come. The rate and degree of maintenance touchups will depend on the climate and the type and condition of the wood.
The US Forest Service suggests a few other variables that should be considered:
- Exterior finishes will last longer if there is shade around the building. If this is not possible, what about considering a long covered porch, or 4 to 6 foot overhangs?
- If heavy snow is common, think about putting 2 to 3 feet of fieldstone on the lower courses of your building. Standing snow should also be removed from decks and porches.
[ Back to top ]
COVERAGE & CLEANUP
One gallon of Velvit CDF covers 250-300 sq.ft. on the first coat, 300-500 sq.ft. on additional coats.
Clean brushes with a mild mineral spirit, paint thinner or brush cleaner designed for use with oil finishes. Citra-Solv also works great as an alternative brush cleaner and all purpose solvent—petroleum free with minimal environmental impact.
[ Back to top ]
PRECAUTIONS
Place used rags in a closed metal container to avoid combustion. Though Velvit CDF is a vegetable based product, like all fine wood finishes, it contains mineral spirits, a petroleum distillate, to keep it from drying in the can. Being an exterior product, adequate ventilation should not be a problem. Sensitive persons should avoid prolonged contact with the skin. Once cured, there is little to no discernable smell.
Close cans by pressing at various points around the edge, rather than hammering. Keep stores cans out of reach of children. If swallowed, do not induce vomiting; call a physician immediately.
[ Back to top ]
| 
