H

Hard dry
Full cure of a coating: usually 72 hours to 5 days.

Hardeners
Substance or mixture of substances added to a resin to promote or control the curing reaction by taking part in it.
Syn. Crosslinking agent, Curing agent

Haze
Dulling of a paint surface due to material that has exuded to the surface, fine solvent popping, roughening of the surface because of flocculation or poor coalescence, microvoids, etc ...

Heat stabilizer
Additive which increases the ability of the coating to withstand the negative effects of heat exposure. Heat stabilizers are used to increase the overall service temperature of the polymer.

Hiding agent
See Opacifier

Hiding power
Ability of a paint to mask the color of the surface to which it is applied.

High build
Coating which can produce a thick film in a single coat.

HLB (Hydrophilic-liphophilic balance)
Ratio between hydrophilicity and hydrophobicity of surfactants. HLB gives information about the behaviour of these surfactants in various processes.

Humectant
Soluble compound used to preserve the moisture content.

Hydrophilic
Substance which absorbs or has an affinity for water.

Hydrophobic
Substance which does not absorb or exhibit an affinity for water.