88
Table 2
CHEMICALLY RESISTANT PAINTS
Common description
Chlorinated rubber paint
Bitumen paint
(BS.3416)
Tar paint (B.S. 1070)
Epoxyester paint
Epoxy (two-part) paint
Coal tar/epoxy or pitch/epoxy (two- part) paint
Urethane (two- part) paint
Urethane/pitch (two-part)
'Neoprene' paint (mainly two-part)
'Hypalon' paint
Composition of medium
Mainly chlorinated rubber, pigmented
variously
Bitumen or tar
Epoxy-resin/ester compositions in a single-part paint Epoxy resin mixed with catalysts just before use
A combination of epoxy resins and coal tar pitch
Urethane resins mix- ed with catalysts just before use Urethane resins com- bined with coal tar pitch
Neoprene, a synthe- tic rubber, is mixed with vulcanizing agents just before
use
Based on 'Hypalon", a synthetic rubber
a
Use
For better com- bination of resistance to weather, water, acid, alkali and some solvents than is given by most high- gloss paits
Where cheap materi- als of good water resistance are requir- ed
To resist mild chemical attack
For thick coats of high resistance to chemicals or aikalis
Where the good water resistance of tar, and the heat and chemical resis- tance of epoxy resins are both required For good chemical weather resis-
and tance
Similar to coal tar/ epoxy: spray-appli- ed
For good chemical and weather resis- tance, in the form of a tough, rubbery coating
For good chemical and weather resis- tance, in the form of a tough, rubbery coating
Comments
Some care in brushing is required, as each cont tends to lift the one before.
Less tolerant of damp surfaces than conventional materials.
Table 3
PAINTS
EMULSION
Some types tend to lift previous coats of con- ventional paints. Moderate resistance to weather; better if the final coat is pigmented with alum- inium. Soften in hot sunlight. Overpainting with other paints difficult.
Resistant to water, acids, oils and many solvents, but most are affected by alkalis.
Chalks fairly rapidly outdoors, but further break- down is slow. Of excellent adhesion to concrete. Used as a basis for floor finishes.
Suitable for lock gates and chemical plant, where exposure to water is severe. Surfaces should preferably be grit-blasted.
May have rather better resistance to weather than epoxy paints. Used as a floor finish and a clear finish for timber.
Recently introduced. Cures even at low tempera ture and high humidities. Has a short pot life.
Frequently used as multi-coat systems, but sing'e coats can be used where conditions are mild eg. [ where there is no splash or spillage, provided care is taken to avoid 'misses'.
As for 'Neoprene' in a wider range of colours.
Common description
Oil-bound dis temper {water paint) B.S. 1053, type A Emulsion paint (polyvinyl acetate* plasticized)
Emulsion paint (polyvinyl acetate copolymer)
Emulsion paint (acrylic)
Emulsion paint (styrene-based)
Emu'sion paint (alkyd)
Basis of emulsion
Drying oils or var- nishes
Polyvinyl acetate with addition of plasticizers
Polyvinyl acetate combined with other polymers Acrylic resins
Styrene, styrene- butadiene and simil- ar resins
Alkyd resins
Use
On walls and ceilings
On walls and ceilings
On walls and ceilings
On walls and ceilings
On walls and ceilings
On walls and ceilings but not on wet plasters, renderings, brickwork, etc., which are alkaline
Comments
The traditional material for interior decoration. The best modern examples are able to withstand moderate scrubbing & weather fairly well outdoors. Similar in many ways to distemper, but better able to withstand scrubbing and weathering. Most of the emulsion paints at present avail- able in the U.K. are based on polyvinyl acetate. Similar to plasticized polyvinyl acetate emulsion paint; there is insufficient long-term evidence to decide whether it is superior in qualities. Similar to polyvinyl acetate emulsion paint; may offer better adhesion and resistance to weathering, but there is no long-term evidence that this is so. Manufacture has been largely discontinued in U.K.
Few brands now availab'e; the lack of resis. tance to alkali was too great a handicap.
* Emulsion paints based on polyvinyl acetate incorporate a plasticizer and are described as 'externally plasticized', those based on copolymers are termed 'internally plasticized', being themselves sufficiently plastic without incorporating a supplementary plasticizer.
THE HONG KONG & FAR EAST BUILDER—VOLUME 17, NUMBER 3
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