How to Prepare Wood for Staining
The durability and beauty of any stain work rests on the stain quality and the preparation of the surface. Just as you cannot brush your shoes without dusting them off first, you should not stain a wood surface without cleaning it.
Homeowners spend very little time on surface preparation. Instead, they spend lots of hours in selecting the right color for the stain product. However, professionals know that when you prepare well, your stain will last and it will prevent you from having many problems. To properly prepare your surface, follow the steps below.
Look for obvious defects in construction and other problem areas. The surface needs to be in good condition and the wood should not be rotting, decaying or eroding. Check also for surface contamination like cedar bleed, mildew stains, chalkiness, and dirt. Remove contaminants before stain application, but remember no single cure exists for all the surface issues.
Test the surface
Always perform a tape test to ensure that the wood is ready for staining. First, press a tape against the surface that needs to be stained and tear it and examine the back part. When loose wood fibers or old stain is on the tape, it can indicate a moisture issue. Since excessive moisture in the wood accounts for most of the issues like premature wood erosion, peeling, decay or rot, the surface needs to be dry when you want to stain; and the moisture reading should be at 15% or less.
The surface needs to be placed in a position that makes it not to absorb excess moisture once staining is done. A solid bodied paint or stain won’t peel unless the moisture forces it off. Other issues such as premature wood erosion may be caused by bad weather moisture. Before you stain, replace decayed or rotting wood and remove eroded wood fibers and loose stain by power washing, scraping or sanding the surfaces.
Dealing with contaminants that appear on the surface
When the surface is as it should be, re-inspect for mildew stains, dirt, chalkiness, cedar bleed and any other substance. Identify each contaminant since each one requires its treatment. Dirt, mildew stains, soot and other pollutants usually appear as specks or black spots on the surface.
To identify the right treatment, use some amount of household bleach on the black spots. If the dark spots lighten quickly, know that mildew stains are present, soot, dirt and other pollutants may not change color.
Eliminating dirt and mildew stains
To effectively remove dirt, mildew stains, and other pollutants, use a cleaning detergent that has sodium hypochlorite found in household detergents, sodium metasilicate which is a wetting agent, and calcium hypochlorite an oxidizing agent like Cabot Problem-Solver Cleaner. All these ingredients are necessary because they all play different roles in getting rid of the substrate.
You can detect chalkiness by rubbing your hand over the wood surface, or you can use a clean cloth in place of your hand. If you feel some flakiness on your cloth or hand, the previous stain is breaking down to cause chalking. Before reapplying the stain, remove the chalkiness using a detergent solution that comprises of sodium metasilicate.
Cedar bleed is identified by a reddish brown discoloration that makes old stain appear to be uneven or blotchy. To test its presence, apply a ferrous sulfate solution to the surface that is discolored, and if the solution turns to blue-black from its natural color, the wood has cedar bleed. Ferrous sulfate is not found in retail shops that easily, you have to source I from other stores. Cabot Problem-Solver Brightener which is an oxalic based solution will remove the discoloration easily, and it also removed the metal and nail stains.
Additionally, Cabot Problem-Solver Primer is used on wood species like red cedar, mahogany, redwood, and fir. When it is applied immediately to new, unseasoned, mill glazed dry siding, it has exceptional great adhesive properties.
Be careful when pressure washing.
If you are uncomfortable with sanding or scraping loose stain, rent a pressure washer from a local home store. Pressure washing is not necessary the ultimate process because sanding and scraping are necessary for some occasion, using the correct technique when pressure washing will ensure most jobs are done well. When you are cleaning wood, use 40 degrees and 500 psi. If you go beyond this measurement, you will have poor results and even risk damaging your wood.