Grain Popping - How and Why
Most floor finishers have used water-popping for many years in many different ways. Grain popping is a procedure used to open the cells of the wood for a couple of reasons.
One reason is to increase the penetration of pigmented stain into the wood cells of open grained woods like oak and ash to achieve a deeper more uniform color across the board surface. Other reasons are to remove fine screen scratches before coating or staining on close-grain or dense woods like maple or Brazilian cherry; to aid penetration before staining woods with erratic grain; and to reduce grain-raise prior to applying waterborne stains or finishes on any wood.
Grain popping works by causing the cells of the wood to swell when they are wet, then as they dry “slowly”, the cells remain open. If the floor dries too fast the cells never get to fully open. This is why the long, slow dry time is so important. To pop the grain on any wood species or pattern, all that is needed are a vacuum cleaner, a bucket of warm water and clean white cotton cloths.
Vacuum the floor. Working from a bucket, wet the floor with a rag, as if staining. Wipe excess water immediately with a clean white cloth. Work with the grain of the wood wetting and wiping as you go across the floor. When wiping up excess water on the second stretch of the floor, wipe dry continuing into the previous stretch. This will unify the dampness without leaving excess water on the surface. Work across the floor drying as you go. The objective is to wet only the top few cells of the wood.
Work with windows closed and fans off. You want the floor to dry slowly and uniformly. Excess air flow will cause the floor to dry faster in some areas than in others.
How long should the wood dry before staining or coating? The best results are achieved by allowing overnight dry under normal drying conditions. In very hot, dry climates (such as in Arizona) overnight dry may not be necessary. Make your own shop tests to see what works best for your area and seasonal conditions.
On jobsites where there is a lack of heat or dampness from wet work being done by other trades, the drying may be considerably slowed or stopped. All trades should be out of the area and no foot traffic on the floor at any time until the job is completed. As for the floor itself, grain popping works best when the cracks and joints in the floor have been trowel filled. The filler keeps water out of cracks which helps accelerate uniform drying. The best drying will occur when the outside air temperature is between 65-70 degrees and the relative humidity is between 45-55%. If rain, fog, cool or damp conditions exist, try to get jobsite conditions up to room temperature. If not, open windows slightly to allow some air movement. If it is hot and dry outside, stop all ventilation so the water will have the time it needs to work. If raining or snowing, keep the heat in the house at room temperature and close the windows. If outside conditions allow, turn off air conditioning since it dries the air and can also dry the water too fast.
Some Do’s and Don’ts to help avoid problems:
• No direct ventilation such as fans or direct air flow. Fans will cause some areas to dry faster than others resulting in an uneven appearance.
• Eliminate all foot traffic to reduce dirt in the grain or flat spots in the surface appearance.
• Allow sufficient dry time so stain color will take as deep as possible. Careful application, wiping and blending of the water results in a more uniform job.
• When popping the grain to reduce grain raise before waterborne stains or finishes are applied, hand sand the floor lightly with a used 120 or 150 grit sandpaper and vacuum. Do not screen or otherwise machine smooth the floor. Screening will re-expose the closed wood cells and defeat the water popping effect.
• Before staining or coating: Allow complete drying, Allow minimum foot traffic on the floor and do not screen.
Generally, problems that arise after floors have been water popped, such a peeling or uneven stain or color appearance will require resanding as a repair. For this reason it is recommended that this process be given time to work and dry.
Water popping can solve many application issues. Used appropriately, it is a process that can be the floor finishers best friend.
Most floor finishers have used water-popping for many years in many different ways. Grain popping is a procedure used to open the cells of the wood for a couple of reasons.
One reason is to increase the penetration of pigmented stain into the wood cells of open grained woods like oak and ash to achieve a deeper more uniform color across the board surface. Other reasons are to remove fine screen scratches before coating or staining on close-grain or dense woods like maple or Brazilian cherry; to aid penetration before staining woods with erratic grain; and to reduce grain-raise prior to applying waterborne stains or finishes on any wood.
Grain popping works by causing the cells of the wood to swell when they are wet, then as they dry “slowly”, the cells remain open. If the floor dries too fast the cells never get to fully open. This is why the long, slow dry time is so important. To pop the grain on any wood species or pattern, all that is needed are a vacuum cleaner, a bucket of warm water and clean white cotton cloths.
Vacuum the floor. Working from a bucket, wet the floor with a rag, as if staining. Wipe excess water immediately with a clean white cloth. Work with the grain of the wood wetting and wiping as you go across the floor. When wiping up excess water on the second stretch of the floor, wipe dry continuing into the previous stretch. This will unify the dampness without leaving excess water on the surface. Work across the floor drying as you go. The objective is to wet only the top few cells of the wood.
Work with windows closed and fans off. You want the floor to dry slowly and uniformly. Excess air flow will cause the floor to dry faster in some areas than in others.
How long should the wood dry before staining or coating? The best results are achieved by allowing overnight dry under normal drying conditions. In very hot, dry climates (such as in Arizona) overnight dry may not be necessary. Make your own shop tests to see what works best for your area and seasonal conditions.
On jobsites where there is a lack of heat or dampness from wet work being done by other trades, the drying may be considerably slowed or stopped. All trades should be out of the area and no foot traffic on the floor at any time until the job is completed. As for the floor itself, grain popping works best when the cracks and joints in the floor have been trowel filled. The filler keeps water out of cracks which helps accelerate uniform drying. The best drying will occur when the outside air temperature is between 65-70 degrees and the relative humidity is between 45-55%. If rain, fog, cool or damp conditions exist, try to get jobsite conditions up to room temperature. If not, open windows slightly to allow some air movement. If it is hot and dry outside, stop all ventilation so the water will have the time it needs to work. If raining or snowing, keep the heat in the house at room temperature and close the windows. If outside conditions allow, turn off air conditioning since it dries the air and can also dry the water too fast.
Some Do’s and Don’ts to help avoid problems:
• No direct ventilation such as fans or direct air flow. Fans will cause some areas to dry faster than others resulting in an uneven appearance.
• Eliminate all foot traffic to reduce dirt in the grain or flat spots in the surface appearance.
• Allow sufficient dry time so stain color will take as deep as possible. Careful application, wiping and blending of the water results in a more uniform job.
• When popping the grain to reduce grain raise before waterborne stains or finishes are applied, hand sand the floor lightly with a used 120 or 150 grit sandpaper and vacuum. Do not screen or otherwise machine smooth the floor. Screening will re-expose the closed wood cells and defeat the water popping effect.
• Before staining or coating: Allow complete drying, Allow minimum foot traffic on the floor and do not screen.
Generally, problems that arise after floors have been water popped, such a peeling or uneven stain or color appearance will require resanding as a repair. For this reason it is recommended that this process be given time to work and dry.
Water popping can solve many application issues. Used appropriately, it is a process that can be the floor finishers best friend.
