GLOSSARY
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P
PAINT BRUSH BRISTLES
Natural or synthetic fibres bundled together
and attached to a handle for use in soaking up paint and spreading it
onto a surface. Natural bristles are usually hog bristles or horse
hair. Because natural bristles can be softened by the water in water-borne
coatings, these brushes are most effective for application of solvent-borne
coatings. Synthetic bristles are usually nylon, polyester, or
blends of these. Because some solvents can have a detrimental effect
on synthetic bristles, these brushes are most effective for application
of water-borne coatings.
PAINT FAILURE
The condition of a paint film at the
end of its useful life; the premature deterioration of a coating. All
paints must fail eventually, but the method of failure and the suitability
of the surface for cleaning and repainting are the important factors
that must be considered when undertaking any remedial action.
PAINT HEATER
Device for lowering viscosity of paint
by heating it prior to application.
PAINT MITT
A painting tool worn on the hand. This
fabric-covered mitt is dipped into paint and then used to apply the
paint by grasping or rubbing the surface to be painted.
PAINT PAD
A paint application tool designed to
apply paint by a wiping action. It consists of a flat square or rectangular
backing covered with very short-napped synthetic fiber and connected
to a handle.
PAINT REMOVER
A mixture that softens old paint or varnish
and permits it to be removed with a scraper. Paint removers also are
called chemical strippers and usually contain solvent, wax, and other
chemicals. Paint removers are suitable for removing most oil-based paints,
thermoplastic paints, and latex emulsion paints.
PAINT ROLLER COVER
A tubular sleeve consisting of a hollow
tube or core covered with natural or synthetic fibre materials. Natural
fibre materials are sheepskin, lamb’s wool, and mohair; synthetic
fibre materials include acrylic, polyester, and nylon.
PAINT ROLLER COVER NAP LENGTH
The length of the fibres of the material
on a roller cover. Different nap lengths are used depending upon whether
the surface being painted is rough or smooth. Short-nap covers (1/4
to ½ inch) are used for painting smooth surfaces; long-nap covers (3/4
to 1-1/2 inches) make it possible to work paint into crevices, pits,
and other irregularities of rough surfaces.
PAINT ROLLER TYPES
- DIP ROLLER- Paint is supplied by dipping the roller into a tray or a 5-gallon pail of paint. Excess paint is removed by rolling the dip roller over the roughened ramp of the paint tray or over a mesh grid attached to the 5-gallon pail.
- FOUNTAIN ROLLER - The roller has a hollow core that is filled with paint. Pores in the core allow the paint to saturate the outer fabric covering.
- PRESSURE-FED ROLLER - Paint is continuously pressure-fed through a supply hose to the centre of the roller. Like the fountain roller, pores in the core allow the paint to saturate the other fabric covering.
PAINT THINNER (MINERAL SPIRITS)
A petroleum-derived solvent used for
thinning paint. Odourless mineral spirits have been refined to remove
some odorous constituents.
PAINT THICKNESS GAUGE
The wet or dry thickness of a coating
on a substrate. Film thickness is measured in thousandths of an inch
or mils.
PALM SANDER
A power sander so named because it fits
comfortably in the palm of the hand. Palm sanders are handy for finishing
woodwork.
PARAPET CLAMP
A device designed to fit over and clamp
onto a parapet along the perimeter of a roof or structure. It is used
for rigging scaffolding.
PASTE
Wallcovering adhesive or paste is available
as powder material, which must be mixed with water at the job site,
or premixed material, which is formulated at the factory and ready to
use.
PASTE MACHINE
A machine with one or more rollers used
to apply either adhesive or pre-paste activator to wallcoverings. Paste
machines come in a number of sizes and types, including table and floor
models.
PATCHING PLASTER
A special plaster made for repairing
plaster walls.
PATTERN NUMBER
Indicates the design and colour of a
wallcovering. The pattern number should match for all rolls of wallcovering
used for a job.
PATTERN MATCH
See WALLCOVERING, PATTERN MATCH.
PEELABLE
A wallcovering that can be dry-peeled
and leave a continuous base layer on the surface.
PEELING
Spontaneous dis-bonding of particles
of a paint, varnish, or lacquer film from a surface due to loss of adhesion.
Peeling may result if paint is applied to a damp, greasy, or improperly
prepared surface. For wood and other porous substrates, peeling sometimes
is the result of excessive moisture behind the surface.
PENETRATING FINISH
A finish that sinks into the substrate,
as opposed to settling on the surface.
pH
A measure of hydrogen ion concentration
indicating whether a solution is acidic (pH less than 7), neutral (pH
equals 7), or alkaline (pH greater than 7). The further the pH is from
7 the more acidic or alkaline the solution is. A change of one pH unit
represents a ten-fold change in hydrogen ion concentration. For example,
pH 4 is 10 times more acidic than pH 5 and 10 times less acidic than
pH 3.
PHENOLIC ALKYD RESIN
Alkyd resin system modified with a phenolic resin. Phenolic modifications can perform satisfactorily in water immersion, a service in which unmodified alkyd resins are unsuitable.
PHENOLIC RESIN
Synthetic resin made from phenols and
aldehydes. Phenolic varnishes are made by cooking phenolic resins with
a drying oil. They are widely used in spar varnishes and many enamels;
occasionally used in catalysed coatings.
PHOSPHATING
Pre-treatment of steel and certain other
metal surfaces with chemical solutions containing metal phosphates and
phosphoric acid as the main ingredients. The result is a thin, inert,
adherent, corrosion-inhibiting phosphate layer that serves as a good
base for subsequent paint coats.
PHOSPHORIC ACID
A weak acid sometimes used to remove
light rust from steel and to pacify the steel surface.
PICKLING
Removal of rust and mill scale from steel
by immersion in an acid solution containing an inhibitor. Pickling should
be followed by thorough washing and drying before painting.
PIGMENT
Finely ground, natural or synthetic,
inorganic or organic, insoluble particles that, when dispersed in a
liquid vehicle to make paint, may provide colour and other properties
of paint, including opacity, hardness, durability, and corrosion resistance.
PINHOLE
Coating film defect in which small, pore-like
flaws penetrate one or more coats of paint to expose an underlying coat
or the substrate. This term generally is applied to holes caused by
solvent bubbling, moisture, other volatile products, or the presence
of extraneous particles in the applied film. Pinholes look like pin
pricks in the coating surface.
PINPOINT RUSTING
Tiny, dispersed points of rust that can appear at pinholes and holidays in the coating. Very dense pinpoint rusting can appear on painted steel surfaces where the coating does not completely cover the blast cleaning profile.
PIT
A small hole in the surface of a metal
or other material that is deeper than its diameter.
PITTING
Small holes or pits in the surface of
a metal usually caused by corrosion.
PLASMA SPRAYING
A spray application process in which
metallic or thermoplastic powders are melted in the plasma arc cavity
that contains the gas stream of the plasma gun and sprayed onto the
surface being coated by means of the flow of the plasma jet.
PLASTER OF PARIS
A white, powdery substance formed by
heating gypsum. When mixed with water, it forms a paste that sets quickly.
PLASTIC-COATED WALLCOVERING
Wallcovering with a coating of transparent
plastic to withstand washing and resist stains.
PLASTICIZER
A substance added to paint, varnish,
or lacquer to soften and add flexibility to the dry or cured coating.
PLURAL COMPONENT SPRAYING
A paint application method that automatically
proportions and mixes two or more components of a paint material in
the process of delivering them to the spray gun. Plural component spray
equipment is used to apply coatings with a pot life that is too short
to permit mixing and application by conventional air and airless spray
equipment.
POLYESTER RESIN
Synthetic resin made from polyhydric
alcohols and polybasic acids, and often dispersed in a suitable monomer.
Alkyd resins are a specific type of polyester resins and may be regarded
as complex esters.
POLYMER
A material that consists of one or more molecular structural units (monomers) repeated any number of times. Types of polymers are
- HOMOPOLYMER - a single type of monomer linked with itself any number of times;
- COPOLYMER - two or more different monomers linked with each other in specific sequences and/or proportions.
POLYMERIZATION
The uniting of two or more small molecules
(monomers) to form one large molecule (polymer, macromolecule). The
new molecule contains repeating structural units of the original molecules.
POLYURETHANE
A film-forming substance produced when
an isocyanate reacts with hydroxyl-containing substances (polyols) to
produce an organic compound known as a urethane. It shows good chemical
and excellent solvent resistance. Abrasion resistance is also outstanding.
Polyurethane coatings can be obtained as air-drying, moisture-cured,
or catalysed types.
POLYVINYL CHLORIDE (VINYL)
A synthetic resin used in the binders
of coatings. Tends to discolour under exposure to ultraviolet radiation.
Commonly called "vinyl".
POPPING
The development of craters or pinholes
in a coating of paint or varnish while it is curing. See CRATERING,
PINHOLE.
POROSITY
(1) The ability of a surface to absorb
a liquid, vapour, or gas. (2) The presence of numerous visible pits
or pinholes in concrete.
POST-CURING
An after-application treatment (liquid
curing solution, heat, radiation, etc.) that enhances a coating’s
level of cure or one or more of its other properties.
POT LIFE
The useful life of a coating material
after the initial opening of its container, or after catalysts, activators,
hardeners, or other ingredients are added to initiate the curing reaction.
Pot life often depends on temperature and humidity.
POWER FILE
A power tool with a straight or curved
file used to remove burrs from metal, or brush spots from wood, plastic,
or fibreglass surfaces.
POWER TOOL CLEANING
The use of power impact, scraping, sanding,
and brushing tools to remove loose paint, loose rust, and loose mill
scale and other contaminants.
POWER WASHING
The use of pressurized water (typically
less than 5,000 p.s.i.) to remove surface contamination and debris from
steel, concrete, and wood surfaces.
POWER WIRE BRUSH
A power tool with a brush made of knotted
or crimped wire bristles in the form of a wheel or a cup.
PRE-TRIMMED WALLCOVERING
Wallcovering from which selvage has been
trimmed at the factory.
PRE-PRIMER
Coating developed to penetrate old, loose
coatings, such as aged, red lead primers, and seal them to the substrate.
Pre-primers have low molecular weight and low viscosity, and they are
clear or lightly pigmented. They have high penetrability, but cure to
a hard, tough polymer.
PRESERVATIVE
Substance added to a paint to prevent
growth of micro-organisms both in the can and on the applied paint film.
PREVENTIVE MAINTENANCE PAINTING
Periodic touch-up painting, spot-repair
painting and/or application of additional full coats of paint before
significant deterioration occurs.
PRIMARY COLOURS
A colour that cannot be produced by mixing
any other two colours. The primary colours are red, yellow, and blue.
All other colours except black and white are blends of these three colours.
PRIMER
- First full coat of paint when two or more coats are applied to a surface. Primers provide adhesion to a new substrate (wood, metal, masonry, or concrete), protect the substrate, and aid in the adhesion of additional coats of paint. The type and condition of the substrate and the total painting system specified for a job affect the selection of the type of primer used.
- In wallcovering, a primer may be applied to the surface to improve the grip (bonding strength) of the wallcovering adhesive.
PRINTING NUMBER
The printing number or dye lot on rolls
of wallcovering indicates whether or not the rolls were printed at the
same time. Since there may be slight differences in the colour, alignment,
and appearance of wallcoverings printed in different print runs, only
rolls from one print run should be used for a job.
PROFILE
The contour or roughness of a surface,
especially after blast-cleaning. Profile is important because it gives
paint an anchor for gripping to the substrate and forming a good, tight
bond.
PROFILE COMPARATOR
An instrument used to determine the profile
of a blast-cleaned surface by visual or tactile comparison of the surface
with a series of reference surfaces having various profile depths.
PROFILE DEPTH
A measure of the profile of a surface
based on the distance between its peaks and valleys.
PROPELLANT
The gas used to expel materials from
aerosol containers.
PSI
Pounds per square inch; a measure of
compressed air pressure.
PSYCHROMETER
A test instrument used to determine dew
point and humidity.
PUMP RATIO
- Multiplier of input pressure that indicates output pressure. This is the ratio of air piston area to fluid piston area.
- For fluid proportioning pumps, the ratio between two fluid piston output volumes per stroke.
PUTTY (glazing compound)
A dough-like material consisting of pigment
and vehicle and used for sealing glass in window frames and for filling
imperfections in wood or metal surfaces.
PUTTY KNIFE (board knife)
A hand tool with a blade 1 to 2 inches
wide. It is used to apply putty or small amounts of other patching materials.
