Glossary - P
Paint deodorants
Aromatic materials which are added to paint to mask paint odour.
Paint remover
A liquid composition that is applied to a dry paint film and softens it sufficiently to permit its removal by scraping.
Parapet
A low wall built along the edge of a roof bridge or other structure; the continuation of the main wall above the eaves level to form such a wall.
Patch prime
The priming of localised bare surfaces when bringing forward, prior to stopping up and/or painting.
Patchiness
This is caused either by different levels of porosity in the substrate or by uneven application. Usually, one more coat will rectify the problem. Before applying, thoroughly clean down the surfaces to remove all dirt, grease and surface contaminants. Rub down with a suitable abrasive, dust off and apply coating.
Pebble dash
A rough finish given to external walls by coating it with mortar or cement and sand and throwing small pebbles onto the surface before it has set.
Peeling
The detachment of paint from the surface in ribbons or sheets. Like flaking, it is the result of loss of adhesion properties.
Performance
A term used to indicate the degree to which a paint system will meet the requirements of any specific job, e.g. an interior quality paint would give poor performance (would have poor durability) if used on exterior surfaces.
Permeable
A paint system which is said to be permeable when it allows water vapour to pass through the paint film, i.e. the paint allows the substrate to breathe.
Petrifying liquid
Usually a dilute emulsion of drying oil and/or varnish in water used as a sealing coat on surfaces under water paint or as a thinning agent for water paint.
Phenolic
A synthetic resin used in the manufacture of some industrial finishes.
Phosphating
The treatment of steel or other metal surfaces or articles with solutions containing phosphates and phosphoric acid to produce a coating which inhibits corrosion and assists paint adhesion.
Picking out
The individual colour treatment of ornamental units and/or mouldings in cornices and similar architectural features.
Picking up
This has two meanings:
- The process of joining up to 'wet' or 'live' edges on lapping.
- The lifting or softening of a previous coat of paint when applying a subsequent coating.
Pickling
The treatment of steel by immersion in a special acid solution in order to remove millscale (acid pickling). Alternatively, a method of removing paint varnish or varnished wallpaper with a strong alkaline solution. Hence any alkaline cleaning solution may be referred to as 'pickle'.
Pier
The supports of the arches of a bridge; area of plain wall between arches or openings. Hence is commonly used to describe any rectangular projection in a wall flank.
Pigment
This powder like substance is one of paint's basic components (the other is the binder). The pigment gives the paint its colour and hiding power. Titanium dioxide is the most important pigment used to provide hiding in paint.
Pillaster
A square pillar, often purely ornamental, projecting from a pier or wall, often in symmetry with a line of columns.
Pinholing
The formation of minute holes in a paint film during application and drying.
Pipe
A tube usually for the conveyance of liquids.
Pitch
- A dark coloured bituminous substance.
- The angle of a sloping roof to the horizontal.
Plan
The horizontal section of a building as shown on a drawing.
Plaster board
A building board having a plaster core between two layers of stout paper.
Plastering
The operation of applying plaster and other similar materials to structures to produce a smooth surface. The normal process consists of three coats:
- Rendering,
- Floating
- Setting
Plastic paint
A plaster composition which can be manipulated after application to produce a patterned or modelled effect. The description should not be used for paints based on synthetic resins.
Pliolite
A synthetic type of resin used in the manufacture of some types of masonry paints. Pliolite is the trade mark of the Goodyear Tire & Rubber Co. Inc.
Pointing
Filling the joints in brickwork or masonry with mortar.
Poise
A measurement of viscosity.
Polymer
This binder is produced from petrochemical feedstocks. The binder's polymer particles are small in size and carried in water. The binder polymer and water mix is known as emulsion.
Poor gloss level on new paintwork
Condensation forming on the surface soon after application can take the gloss of new paintwork. This can be caused by painting in cold, damp conditions or painting outside when rain or frost are imminent. Porous under-surfaces can also absorb gloss and make it appear dull. To remedy, lightly abrade the surface and apply a further finishing coat of paint when conditions more favourable.
Porosity
The degree to which a material will absorb liquids.
Pot life
This refers to the period during which a two-pack material remains useable after mixing.
Powdery/chalky surfaces on outside paintwork
Powdery or chalky old paintwork is caused by the paint film wearing away due to exposure to weather. This natural erosion of the paint coating can often be removed by thoroughly washing down prior to repainting. If washing doesn't remove a chalky surface, seal with primer before painting, or in severe cases remove the chalky surface entirely.
Powdery/chalky surfaces on plaster
Powdery and chalky surfaces are quite common in older properties that have been painted with distemper or white wash. You should completely remove these coatings by washing with warm water and a detergent solution. Rinse with clean water and change the water regularly. If the surface still remains slightly chalky, seal with an appropriate Dulux primer or plaster sealer prior to finishing.
Powdery/chalky surfaces on previously painted exterior masonry
Brick and masonry surfaces painted with cement-based paint will eventually corrode and become powdery or chalky. Even unpainted pebbledash or render can become powdery with age. In each case, ensure the surface is sound, clean and dry. Remove all loose material with a stiff brush or paint scraper. If powdery or chalky residues still remain, stabilise the surface with a coat of Weathershield Stabilising Primer. However, don't use a stabilising solution on new or sound bare rendering that has never been painted. A well-thinned first coat of the appropriate Weathershield Masonry Paint is usually all that is required.
Pre-treatment
The initial treatment of a surface prior to painting, e.g. treatment of galvanised metal with mordant solution or sterilising surfaces with fungicidal solution.
Pretreatment
Usually used to indicate the chemical treatment of bare metal prior to painting.
Primer
The first coat of paint applied to a surface which is then the foundation for subsequent coats.
Purlin
Member laid horizontally across the main rafters or roof trusses and supporting the common rafters.
Putlog
A short piece of timber or tube used in scaffolding to support the boards.
Putty
A composition usually made from linseed oil and whiting and used mainly for bedding glass into primed wooden window frames.
PVA
Abbreviation for Polyvinyl Acetate which is used as a medium in emulsion paints.
Pvc
Pigment volume concentration. The ratio of the volume of pigment to the volume of total non-volatile material (i.e. pigment and binder) present in a coating. The figure is usually expressed as a percentage.