Hair Cracking – Very narrow cracks in paint or varnish films.

Hardboard - A generic term for a smooth or textured grainless panel manufactured primarily from compressed wood fibers. Used as exterior siding.

Hardener – Curing agent; promoter; catalyst.

Hardness – The degree to which a material will withstand pressure without deformation or scratching.

Hardwood - Trees that have broad leaves (in contrast to conifer or softwoods). The term has no reference to the actual hardness of the wood. Examples are: oak, maple, ash, beech, walnut, and hickory.

Hiding Power – The ability of a paint to completely hide a surface.

High Flash Naphtha – Flammable aromatic solvent having a higher flash point than most naphtha such as V.M. & P.

Hold Out – Ability (or property) to prevent soaking into substrate.

Holiday – Pinhole; skip; discontinuity; void.

Hot Spots – Spots in plaster caused by improper mixing; will cause a chemical reaction with paint and create “burning” spots.

Hot Spray – Spraying a material that has been heated to reduce viscosity.

Hue – Designates the same of a color, such as red, blue, green.

Humidity – Measure of moisture content in the air.

Hydraulic Spraying – Spraying by hydraulic pressure (see Airless Spraying).

Hydrogen Peroxide – A bleaching compound.