Home Archive Stain Aesthetics & Corrections for Hardwood Floors
Home Archive Stain Aesthetics & Corrections for Hardwood Floors

Stain Aesthetics & Corrections for Hardwood Floors

By Brett Miller, NWFA Vice President Technical Standards, Training & Certification

 

A major advantage of real wood floors over other flooring options is the ability to refresh them over time, or even to update their look entirely. Because real wood is a product of nature, its appearance will change over the years, including its color. Some wood species will get darker, while others will get lighter. This is a normal process that adds to the beauty and warmth of real wood floors, but there are some color changes that are not normal and that can be corrected.

 

Color Inconsistencies

Identification

Color inconsistencies are defined as any color changes that occur in the finish or colorant system.

 

Causes

Color inconsistencies can have a variety of causes, as follows:

  • Many film-forming finishes, natural penetrating oils, waxes and colorants may amber/yellow, fade, lighten or patina in appearance over time. This is normal and should be
  • Direct exposure to light may change the color of finishes or colorants over time. This is a natural change, and should be taken into account when selecting flooring, finishes and color systems.
  • Aniline dyes are not colorfast, meaning they may fade over time or when exposed to
  • Finish applied over an uncured coating or stain, causing color-bleed or color-pull into the finish system.
  • Color-bleed from one section of the floor into another, often through taped-off areas or where stains or colorants leached into areas
  • Floors finished with the fuming process that have been covered, preventing the chemical to adequately evaporate, resulting in discolored areas of the
  • Water-based finish top-coats applied over oil-based sealers that have been sanded through during the intercoat abrasion
  • Repairs in a finished floor that did not follow the previous finish or application processes or that do not match aged/older
  • Improper cleaning products, dilutions or application used on the floor
  • Area rugs and non-slip area rug pads that are incompatible with the wood floor finish systems, or have been placed over uncured finishes can leave discoloring stains, blushing of the finishes or impressions in the finish as well as the wood.
  • Chemical, urine or moisture

 

Cures

  • To minimize finish color change, reduce the floor’s exposure to direct
  • When a recoat will not remove the discoloration effectively, resanding may be necessary.
  • When resanding will not remove the discoloration effectively, or when the wood or flooring system is damaged beyond salvaging, replacement may be
  • When maintenance-related stains have damaged the finish only, a recoat may be sufficient to remove the discoloration.
  • Isolation repairs may be an option when attempting to match color variation within smaller areas of the floor.

 

NWFA blotchy stain
Blotchy stain/colorant.

Blotchy Stain/Colorant

Identification

Blotchy stain or colorant is defined as the appearance of an inconsistent stain or colorant from one area of a finished floor to another. Color tones may vary from board to board or within individual boards due to natural variances within the wood, but in general stained/colored floors should be uniform in color.

 

Causes

Blotchy stain or colorant can have a variety of causes, as follows:

  • A physical property of the wood species itself (such as maple, black cherry, pine) whereby it does not evenly accept stain or
  • Inconsistent sanding from one area of the floor to
  • Inconsistent or uneven water-popping from one area of the floor to
  • Inconsistent stain/colorant
  • Finish applied over an uncured coating or stain, causing color-bleed or color-pull into the finish system.
  • When resanding, not all of the previous coating system was sanded off prior to
  • Contamination remaining on the flooring surface prior to

 

Cures

  • No remedy is necessary when the natural characteristics of the wood species cause the blotchy
  • Resanding the entire floor may be necessary when inconsistent sanding, uneven water popping, inconsistent stain/colorant application, previous coatings were not removed or when contamination is
  • A preventative measure prior to stain application is to water-pop species that are prone to blotchiness to help reduce the

 

NWFA picture framing
Picture framing.

Picture Framing/Halo

Identification

Picture framing/halo is defined as the edges of the room appearing to be a slightly different color than the rest of the room.

 

Causes

Picture framing/halo can have a variety of causes as follows:

  • Improper sanding The degree to which stains color a wood floor is based largely on the sanding process, abrasive selection and sequence used to sand the floor.
    • Sanding the edges of the room with an abrasive grit different from the abrasive grit used to sand the
    • Inadequately blending the scratch pattern of the floor’s perimeter with the field of the floor in the final sanding
  • Inconsistent or uneven water-pop/stain/sealer/finish application around the perimeter of the
  • Improper curing around the perimeter with site-cured UV
  • Repairs around the perimeter not blending with the main field of the

 

Cures

  • For improper sanding sequence, resand affected
  • For stain/color/sealer-related causes, a complete resand may be
  • For finish-related causes, a recoat or complete resand may be
  • For UV curing-related causes, a recoat or complete resand may be

 

NWFA stain bleed back
Stain bleed back.

Stain Bleed Back

Identification

Stain bleed back occurs after the initial application of the stain, where the stain seeps back to the surface of the wood. This may happen at board seams, with open-grain species, tight grain, knots or burls.

 

Causes

Stain bleed back can have a variety of causes, as follows:

  • A change in moisture content and/or jobsite environmental conditions causing higher moisture content levels within the flooring. The resulting swelling of the flooring can force out any undried stain residual within or between
  • Jobsite conditions too hot or too cold during stain application may alter the intended application and dry
  • Pouring stain directly onto the floor surface during application and allowing pools of stain to sit onthe floor surface long enough to run down the cracks between boards, or soak into the open grain of ring-porous woods like oak.
  • The space between boards allows for stain penetration below the surface of the floor, and between the The abundance of stain remaining below the floor surface is not allowed to dry at the same rate as the stain on the surface, often remaining wet for longer periods of time. After the surface dries, the wet leftovers start to seep, by capillary action, back to the surface.
  • The open grain of some species may absorb an abundance of stain into the cell cavities of the Much of the stain absorbed deep into the cell cavities is not allowed to dry at the same rate as the stain on the surface. After the surface dries, the wet leftovers start to seep, by capillary action, back to the surface.
  • Previously stained areas on the floor where stain does not completely sand
  • Applying water-based sealer or finish to oil-based stained floors that are not adequately The oil-based products migrate from below to the surface of the floor resulting in a spider-type effect under the coating.
  • With factory-finished floors, the undried finishes, pigments, stains or colorants that are absorbed into open grain, knots, checks, burls or other open voids during the application process may sometimes not dry at the same rate as it does on the surface.
  • A gain in moisture can cause wood cell cavities to swell, squeezing out the undried residual to the surface of the boards. In these cases, the surface film-finish will be pushed upward into a bubble or smear onto the floor surface.

 

Cures

  • When stain bleed back occurs, address it before applying the first coat of sealer or finish. Use towels, rags or buff with a non-abrasive white pad to remove excess stain bleed back prior to full dry/cure.
  • When stain bleed back has dried, use a mild solvent (virgin mineral spirits, paint thinner or naphtha) in conjunction with a piece of red or white buffer pad to loosen and remove the bleed back. Stain touch-ups then may be When reapplying stain, allow for proper dry times prior to sealer or finish application.
  • If finish has been applied over stain bleed back, completely resanding affected areas may be
  • With factory-finished floors, individual board repair or replacement may be
  • Preventative measures:
    • Trowel filling the entire floor during the sanding process can minimize stain bleed back.
    • Avoid pouring stain directly onto the floor surface during application and allowing pools of stain to sit on the floor surface long enough to run down the cracks between boards or soak into the floor before

 

The National Wood Flooring Association has detailed information about wood flooring color inconsistencies available through NWFA University, an online training platform that is convenient and affordable. More information is available at nwfa.org/nwfa-university.aspx.

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