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Discoloration encompasses all types of surface related effects that lead to unexpected color changes. These include a darkening or gray color from surfactant leaching, white efflorescence on masonry, white or black color over caulk, black color over masonry patches and drywall joint compounds, red color (tannin bleed) over cedar and redwood, brown or black color (wax bleed) over hardboard, yellowing of white paints, a wide range of color change when non-durable organic pigments are used as tinting colorants, and a premature loss of color when paints are applied over heavy chalk residue.
Color changes are used as indicators for determining the cause of the problem. Some can be paint related, while others are substrate (or surface) related. Color change does not mean that the protective quality of the paint film has been altered.
Two coats Exterior Latex House and Trim Paint |
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The process of making hardboard into lap siding makes the board edges much more absorbent to moisture than the faces. Rain, melting snow and condensation run down the face of the siding and collect at the drip or bottom edge. If the edges are not properly sealed, this moisture can be absorbed into the board. The expansion and contraction of the hardboard caused by seasonal temperature changes and moisture absorption create larger spaces in the board which leads to board decomposition and delamination. Other contributors to moisture penetration are areas where nail heads have fractured the board surface and butt ends that were cut and not properly sealed during installation.
Severely damaged boards must be replaced. Some board decomposition can be tolerated; however, these will show as major blemishes on the newly applied topcoat. The use of sandpaper should be done sparingly so as not to break the board surface.* Spot priming followed by a full coat of primer is recommended after all traces of surface wax have been removed. (See instructions for "Wax Bleed", Problem #1.)
*Caulk all areas such as nail heads, holes and butt joints.
High gloss systems will make all repair work and blemished areas very visible.
One coat A-100 Alkyd Exterior Wood Primer
Two coats Exterior Latex House and Trim Paint (Flat or Satin) |
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Efflorescence is often seen as a white fluffy deposit of salt crystals on cementitious wall surfaces. It depends on the presence of salt and moisture. The growth of crystals will continue as long as both are present. The salts are present in the mortar blocks or concrete structure and the moisture is usually attributable to some building defect. When emanating from mortar in brick or block buildings, efflorescence will appear as narrow bands corresponding to mortar joints.
Painting should be delayed if efflorescence continues. Salts should be removed by mechanical brushing. The use of water to remove efflorescence will only aggravate the defect. Repair areas where moisture penetrates the wall. Allow walls to dry thoroughly.
One coat Loxon Exterior Acrylic Masonry Primer
Two coats Loxon Exterior Acrylic Masonry Paint |
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Flaking is the lifting of paint from the underlying surface in the form of flakes. It is generally preceded by cracking or checking and will occur over different surfaces. When it occurs over wood, it is usually found on those boards that have an excessive amount of "flat" hard grain pattern. This flat grain pattern is smooth, hard and non-porous. Highly pigmented paints crack and eventually flake when applied to this type of surface. They cannot accommodate the large extremes of expansion and contraction of the wood that are caused by seasonal weather changes. Because of poor paint penetration into the hard flat grain, flaking will occur on these areas.
A light sanding to fresh wood followed by application of a high quality undercoater is recommended. Wood must not be allowed to weather prior to coating. Replace boards that have an excessive amount of flat grain patterns with boards that have an edge grain (e.g., boards with equal amounts of narrow hard and soft grain patterns).
One coat A-100 Alkyd or Latex Exterior Wood Primer
Two coats Exterior Latex House and Trim Paint |
