Testing for absorbency is a way to ensure wood will properly absorb an applied stain. Factors that can inhibit the absorption of a stain include:
This test works best on softwoods, and is especially useful in determining when new wood is ready for staining. It does not work well on exotic hardwoods as they have a limited ability to absorb any stain or water.
Get a glass of water. Stick your fingers into the water. Bring your fingers close to the wood and shake off some droplets. The goal is to shake the droplets off your fingers close to the wood so that they do not drop a far distance and splatter on the surface of the wood. On new smooth cut wood or wood in good condition the water will initially bead up on the surface of the wood. Wood will absorb stain just like it absorbs water and it is ready to accept stain when the droplets start spreading out and soaking into the wood within 2 minutes. If the water beads are still intact with little change after two minutes wait one month and retest. Water is thinner than oil. If the wood will not accept water it is not going to accept oil.
This illustration depicts the difference in absorption between older wood and brand new wood. The older wood absorbed the water almost instantly while after 3 minutes the water beads only slightly grew and size and barely started absorbing into the new wood.
Sample cans can be used for vertical wood absorption testing and for confirming absorbency on wood that has passed a sprinkle test. Sample cans are used to test whether or not Armstrong-Clark can be applied over a prior coating that is not Armstrong-Clark. However, it is important to know that success with absorption over a prior stain does not guarantee long term success. If the underlying stain fails it will take the newly applied stain with it. Armstrong-Clark oil based wood stain cannot go over any water based stains, or any stains with acrylic. It is recommended that prior coatings that are not Armstrong-Clark are removed before applying Armstrong-Clark.
Applying stain to wood with too high a moisture content will ultimately lead to adhesion failure.
The surface of all wood, including newly installed wood, must be dry, clean, and free of dust, dirt, mold, mildew, algae, mill glaze, dew, and pollen. After cleaning sweep off surfaces before applying stain.
Scrub, pressure wash, and sand in the direction of the wood grain. Wear protective gear to protect eyes and skin. Use respirators if sanding. Do not use excessive scrubbing, spray pressure, chemical strength, or chemical dwell time as you can damage the wood resulting in furring or raised grain.
Wear protective gear to protect eyes and skin. NEVER mix oxalic acid/ brightener and bleach as a harmful and toxic gas reaction occurs. Do not mix liquid bleach and oxygenated bleach (sodium percarbonate) as they will accelerate a reaction rendering your chemicals useless.
Be sure to change sand paper in a timely manner as recommended by manufacturers. As the sandpaper is used it wears down and eventually performs as a finer grit. For example, an 80 grit can perform like a 120 grit if it is not changed.
We typically do not recommend sanding hardwoods unless the wood is older or the sanding is otherwise necessary. After sanding professionals will often use acetone to open up the pores for better absorption. However we do not promote the use of strong chemicals like acetone as they can have adverse health effects.
When scrubbing use a mid-stiffness bristle brush (like a truck brush). Do not use a stiff bristle brush. Do not scrub excessively hard. Either a hose or a light pressure wash can be used to rinse cleaning chemicals off the wood.
Pressure washing should never be used as a means to remove prior coatings, dirt, or grime. Excessive pressure can destroy your wood. Think of pressure washing as a more effective means to rinse cleaning chemicals than a hose. Let cleaning chemicals do the work of breaking down contaminants on the surface of wood, not water pressure. Remember, water dug out the Grand Canyon, imagine what it can do to wood. Too much pressure will “raise the grain” and/or create wood fur.
Most advice regarding pressure washing revolves around the psi of the machine, the angle of the stream coming out of the machine (stream or fan width), and the distance to keep the nozzle from the wood. For example, most advice for cleaning wood states using 1000-1200 psi, with a 45 degree tip, 10“-12” from the wood to prevent damage the wood. If you use a 65 degree tip you may be able to get down to 6“-10” from the wood without damaging the wood.
Generally speaking softwoods and hardwoods should be approached with different pressures of water. Some experts advise 500psi for softwoods like pine or cedar, and no more than 1200 psi for hardwoods like mahogany or ipe.
To view YouTube video featuring Michael Hinderliter of PowerWash.com
The black numbers in the chart are orifice sizes for the tip on the end of the pressure washing wand. The blue numbers represent the gallons per minute rating of the machine, and the red numbers represent the PSI rating of the machine.
Always read the container for application and precautionary instructions. Typically, you are instructed to wet down the wood for a wet-on-wet application of stripper. Be very careful when applying stripper with a sprayer not to get the spray anywhere you do not want it, especially on painted surfaces like the side of a house. We would recommend taping off and covering painted surfaces and covering vegetation when stripping. Even if you are careful to contain a spray application, you may not be able to control chemicals that may get sprayed or splashed off the surface during the rinsing process. This can be especially damaging when power washing where spray may rise high enough to take the paint off window screens.
When it is time to rinse you can test scrub a small section to see if you need to let the stripper sit a little longer before you rinse. Sometimes a second application of stripper is required.
When using a stripper, there is no need to use a cleaner. Typically there shouldn't be any mold after a stripper is applied. However, if wood was not properly prepared before the prior application of stain, mold may have grown underneath the stain leaving residual mold even after using a stripper. In this instance, spot treat as needed with a 3:1 (water: bleach) solution until mold is gone. Hose off thoroughly.
It is important to understand that the stripping process takes moisture out of wood. If you apply a caustic stripper, you must always apply a brightener which is slightly acidic to neutralize the pH of the stripper. Apply the brightener while the wood is still wet after rinsing off the stripper. The brightener will also lighten the wood back up from the darkening as a result of stripping. Oil based wood stains like Armstrong-Clark will replace the moisture removed in the stripping process.
Review your wood to see if there are any pre-preparation needs that may need to be addressed before you start cleaning the wood.
Both mold and tannin present themselves as a variety of black stains. Tannin stains are often confused for mold or mildew. This is a common misdiagnosis on certain woods like redwood. Dirt can also look like a coat of black on the surface of wood. If the first cleaning does not remove all spots you can retreat the entire surface or spot treat as needed. Understanding what your black spots are will determine what type of cleaner you will need.
To test whether a black stain on the surface of wood is mildew, tannin, or dirt conduct the following test.
Treating Mold, Mildew & Algae
One of the more important considerations in cleaning wood is the presence of mold, mildew, or algae. Regardless of whether or not these can be seen on new wood, new wood should be treated as if it had these growths. New wood is often stacked and bundled while there is still a lot of moisture in the wood. Sometimes this wood is wrapped in plastic which creates a greenhouse effect for hidden mold and mildew growth. Although the growth may not be visible, there is a very good chance that live spores are present on the surface of the wood.
Treating mildew and molds can be tricky. Mold and mildew will often grow on a film of dirt and pollen that is sitting on the surface of wood. Most treatments may be able to treat surface growth, but they do not necessarily kill the root of mildews and molds that have grown into the wood. To kill the roots you need a specifically formulated product you can purchase at a hardware store like Concrobium or Jomax.
Pitch is a yellowish brown sap often found coming out of knots in wood like southern pine or douglas Fir, especially once it gets warmer. Once dry it is white and crusty. Turpentine or mineral spirits on a rag can be used to remove pitch if it is till gooey. Otherwise a putty knife can be used to remove it once it has hardened.
Wood previously coated with a stain other than Armstrong-Clark must have the previous stain removed. If the previous stain is known we recommend using the stripper provided by the same brand. Talk to your local hardware or paint store rep for guidance if the previous coating is not known.
Mask off painted surfaces to protect them during the application or rinsing of cleaning or stripping chemicals. During rinsing chemicals can get blasted onto surfaces from water pressure. Consider covering bushes and plants. When covering plants and bushes be sure not to do so in the hottest part of the day so that they do not overheated and die. Typically we recommend working in the early hours of the day. If covers are not available at least wet down before application and understand this may not be sufficient protection.
In the event that there is wood fuzz or fur on the surface of the wood before staining it must be removed, especially on smooth cut wood.
To remove fur or fuzz you can use 60# - 80# sandpaper. Going much higher in grit count can risk
sealing the pores. Going below 60# you risk removing too much wood. For exotic hardwoods like Ipe
wood restoration professionals often use defelting pads (depicted below). For exotic woods like Ipe
use80# sandpaper, but be careful not to sand down into the wood. For hardwoods you are only
using the sandpaper to remove fuzz off the surface of the wood. Palm sanders and sanding blocks
work well for spindles and tight areas. For variable speed or orbital hand sanders you want to use at
lower speed. Always speak with a local lumber expert to review the requirements for your
specific wood and circumstances.
You can never look at a photo of a color and assume that a particular stain will look the same on your wood. Testing before cleaning will yield an incorrect color. Always test for color once preparation is completed.
When too much stain is applied the nondrying oils saturate the wood and any remaining nondrying oils sit at the surface. Nondrying oils on the surface then prevent the drying oils from locking in the color and drying.
Pollen is mildew and mold food. Mildewcide in stains will prevent mildew and mold from growing in stains, but they will not prevent mildew from growing beneath a stain.
Their higher pigment concentration better protects against the strong UV rays at these elevations. Semi-transparent Chestnut and Natural Oak have approximately 50% more pigment than our other semi-transparent colors. Semi-Solids will provide the most UV protection.
This provides additional protection to the interior of the wood while adding extra protection to the surface. Use a sample can to confirm if your wood can absorb two coats. If two coats a semi-solid color is preferred on a deck mix the semi-solid 1:1 with Natural Tone. This cuts the pigment load in half resulting in two coats of nondrying oil for the interior of the wood and while still only yielding one coat of semi-solid pigment. Two coats of semi-solid pigment will often lead to pigment rubbing off onto shoes and tracking into the house.
Softwoods and Hardwoods typically are very different in absorbing and accepting stain and therefore must be approached very differently.
Rags and other waste soaked with stain can spontaneously catch fire if improperly discarded.IMMEDIATELY after use place all rags and other waste in a sealed water-filledmetal container away from buildings and other combustible materials. Use anempty stain can filled with water if no other container is available.
Armstrong-Clark oil based wood stain can be applied no matter how hot it is and in direct sunlight without having to worry about the stain become thick, sticky, or leaving shiners.
Most stains become thick and viscous in cold weather, and some stains have issues with freezing temperatures in the evening.
Although it needs to be above 50 degrees for application of Armstrong-Clark oil based wood stain, there are no problems with temperatures falling below freezing into the evening after absorption into the wood. However, cold and freezing temperatures will prolong the drying and curing process.
When outside temperatures drop below 50˚F in the evenings keep stain inside to keep warm and apply in the heat of the day. This allows time for the wood to warm up some and burn off any morning dew that may have settled on the wood overnight. Freezing after full absorption will not harm stain but it will lengthen drying time.
Just about every stain manufacture warns against applying stain when rainy weather is expected. This can be frustrating for many, especially during the summer when rain is possible just about every day. Some provide ambiguous warnings like "Do not apply when rain is imminent". What does that even mean? What is the time frame of imminent? Unfortunately this often leaves the consumer uncomfortable and filed with panic if they later hear thunder or otherwise get rain.
Armstrong-Clark oil based wood stains can be exposed to "normal" rain conditions 60minutes after absorption into wood (not 60 minutes after application). In some cases this can be as little as 80 or 90 minutes after application. If heavy rain is expected, we still recommend letting the storm pass and letting the wood dry for 2 days (or until moisture content has gotten down to at least 20% or less).
Unfortunately for hardwoods you may want up to twenty-four hours for absorption before rain precipitates as hardwoods may appear to have fully absorbed and applied stain when in fact the process is still not complete.
Generally speaking, hardwoods only need a single sparingly thin application of stain because of their dense cell structure limits their ability to absorb stain.
AVOID SPONTANEOUS COMBUSTION! Place all rags, sponges, steel wool, and other waste in a water filled metal container after use to prevent spontaneous combustion. Partially fill an empty stain can with water if you do not have a container. Let the rags and other waste sit for at least one week and dispose of according to local regulations. Saturate any large textiles like drop cloths or paper products (used for drop sheets or spray guards) with water. Wash clothes with stain on them - do not leave them lying around. Clean tools with mineral spirits or paint thinner.
An alternative to painter thinner or mineral spirits is using the Dissolve Brush Cleaner & Conditioner. This is non-toxic reusable cleaner. To learn more you can visit dizzolvebruschcleaner.com
Your local paint store or dump can tell you how to dispose of any paint product. Every local has different regulations. There are 10 states, plus Washington D.C., as of 2022 that participate in the Paint Care Program. This is an incredible program for the disposal of paint and stain products paid for via a fee at the time of purchase of any paint or stain product. You can reach their website at https://www.paintcare.org/
Over application simply means that more stain has been applied than wood can absorb.
Test for over application (for horizontal surfaces)
Pour a glass of water into a several random puddles on the surface. Step back and look at the surface of the puddles. You may need to squat up and down and work to get a good angle with the sun to see the surface of the puddle. If the stain is over applied you will see oil floating on the surface of the water (or a rainbow).
What to do if a major cleaning is needed
A cleaning solution can be made with a squirt of hand soap (not dish soap) per one gallon of water. Hand soap is recommended for a cleaning instead of dish soap because dish soap is designed to breakdown oil. DO NOT use bleach. Bleach can remove soft coat stains. DO NOT scrub hard. Use a soft bristle brush or broom and gently sweep the surface of the wood. Use a hose (no nozzle) to rinse the wood. Power washing is not recommended as excessive pressure can remove the stain. NOTE – any scrubbing, no matter how light, can remove some of the stain from the surface of the wood.
