How is water based paint made
How is water based paint made?
The components for a decorative water based paints are different to those for an oil based product and consist of a resin/binder which generally is either Polyvinyl Acetate (PVA) or Acrylic resin containing a coalescent solvent which helps to bind , Pigments (the same as used in oil paints), Thinner (water) plus various additives such as anti-foaming, to stop aeration of the product particularly when applied by roller and leaving pin holes in the surface), thickening agents to give body and biocide(to stop mould growth within the container).
Unlike oil based paints the manufacture of water based paints is easier byway of dispersing pigments and extenders into a solution of water and resin PVE (Polyvinyl Acetate) using high speed mixers.
The range of water based coatings is extensive and manufacturers different formulations depending on their market target.
In general the variants in raw material can lead to product description being similar but product quality can be different with the lower cost material not always offering the same coverage power (opacity) flow (reducing brush or roller marks) and washability.
Lead Based Paints
There was an increased awareness of the environmental issues relating to paint during the late 1960’s when Lead used as a pigment was prohibited from all building paints.
See Health and Safety: Lead based paints.
This directive was instigated by the Greater London Council (GLC) for all paints used on interior trim work. Soon this directive was followed by other major metropolitan authorities.
The exclusion of lead as a pigment and the changes made resulted in decorative building paints becoming easier to apply for both the trade and retail markets.
Lead may be present in properties built before the 1980's especially where the overall paint thickness of the existing coatings is high.
If Lead is suspected then portable Lead Testing Kits will assist. Alternatively, consultancy companies are available to carry out site surveys.
It is essential that any suspected lead based paint removed is bagged up, sealed and labelled 'contaminated material'.
Disposal should be in accordance with local authority instructions.
For further information: https://www.hse.gov.uk/pubns/cis79.pdf
Quality Control and Laboratory Testing
Typical Works Laboratory.
Quality control is the most important of all the areas associates with paint manufacture.
The illustrations show some of the quality assurance tests carried out to ensure the batch to batch production meets the requirements for colour, consistency, durability, application and appearance.
Blue wood staining
Blue wood staining.
As the wood has been stained by moisture, the staining may be difficult to remove, therefore the application of clear or translucent coatings may not be successful, therefore, repainting with opaque finishes maybe required.
For repainting with opaque coatings the following system is suggested.
Preparation.
Check that the moisture content within the wood is below 20%, if not then forced drying may be necessary.
Thoroughly sand down and remove all surface contaminants to leave the surface clean and dry.
Apply one coat of Fungicidal Solution and allow to dry. Re-check the moisture content before painting.
An application of Oxalic Acid (wood bleach) my help to remove part of the staining
Priming /Undercoat /Finishing.
Apply a microporous coating oil or water based, opaque or translucent in accordance with the selected manufactures recommendations.
Microporous paints can be obtained from manufactures such as:
Jotun Paints (Europe) Ltd. Demidekk : https://www.jotun.com/Datasheets/Download?url=%2FTDS%2FTDS__28142__DEMIDEKK+Ultimate+Opaque+Coating__Euk__GB.pdf
Johnston's Paints. https://www.johnstonestrade.com/product/flexible-gloss
Dulux Trade Paints. https://www.duluxtradepaintexpert.co.uk/en/products/products-listing/all
Powder Coated Surfaces Repainting
Powder coated metal
When due to damage, fading or other reasons repainting is require then a specific specification is required.
To apply a conventional oil based paint system is not advisable as adhesion problems can be encountered.
Recommended Specification.
Remove by the most appropriate means, all surface contaminates, dust, dirt, loose or otherwise defected material back to a firm edge .
Feather off all edges with suitable grade abrasive paper to a smooth surface leaving it clean and dry.
Painting.
Priming.
As special adhesion and metal primers are recommended, contact should be made with the selected manufacture to enquire of their specific recommendations and systems.
Note: The following manufactures product range include suitable materials.
Bradite. http://bradite.com
Dulux. https://www.dulux.co.uk/products-listing
Zinsser. http://www.zinsseruk.com/product
Johnstone's https://www.johnstonestrade.com/products
Powder Coated Metal
Powder Coated Metal
Cause
Failure of powder coated hand rails due to mechanical damage or poor preparation of the metalwork prior to coating.[/caption
Causes
Powder coatings have benefits over a conventional oil based building paints, but when problems arise, then special treatment is required. (See specifications).
Other problems can arise besides those illustrated and can be caused during the application process. Bittiness can result in the work not being properly cleaned prior to spraying. Bittiness can also result in weld spatter not being removed and may have to be ground off to provide a smooth surface.
Uneven application is generally associated with incorrect air pressure setup. During application the applicator should maintain continuous gun movement and a high film-thickness in areas, can result in an orange peek effect. If the item sprayed is uncured, then this is suspected then upon impact chipping can occur.
Under curing can also lead to surface bloom.
Remedy
See Powder coating repainting in specifications.
Scaffolding Working at Height
Working at height
Scaffolding should only be erected by qualified personnel who have undertaken training and gained a CISRS (Construction Industry Scaffolding Record Scheme) card.
Under no circumstances should any attempt be made to rectify any observed defects for example couplings that have become loose or broken or split scaffold boards must be reported instantly to the site Management Office and Health and Safety Officer.
Although there are different types of scaffolding products there are three which are generally referred to and are based on the same range of metal tubing and fittings.
Other scaffolding types: Birdcage scaffold - Independent/ Two Pole Scaffold - Putlog Scaffold - Cuplock and Kwikstage.
PPE Must be worn at all times when working at height.
Signwriting
Signwriting & Heraldry
Today, the use of vinyl decals as an alternative to traditional signwriting is common place.
However, there is still a great demand for professional sign writers to carry out one off projects and this skill is available to decorators who have an artistic flare.
Signwriting is not only product of letter writing but also creative artwork including heraldry.
www.vimartsigns.co.uk
[email protected] - [email protected] 07960113799 Nick
See: Signwriter's Tool Box.
Flaking Plaster/Rendered Surfaces
Flaking
Cause
The illustration is the result of the finishing coat of plaster being over polished leaving little or no porosity for the waterbased coating to key onto. It can be seen that there is no latent plaster adhering to the reverse side of the paint flake.
This can also occur when the first coat of a heavy pigmented paint is applied directly onto the surface without thinning to act as a sealer coat.
Remedy
Scrape back all loose material to a firm edge - dampen the exposed plaster with clean water and apply a fine plaster filler to the surrounding area. When dry, lightly rub down, dust off and apply a sealer coat of the waterbased paint followed by the required finishing coats.
Note : for face filling, fine ready mixed plaster filler is suitable.
MDF Sinkage of priming coat
MDF (Medium Density Fibreboard Paint Sinkage)
Cause
MDF is manufactured by breaking down unwanted wood into fine fibres which are in turn mixed with resin and paraffin wax, followed by compressing the mixture under high pressure into panels.
MDF is a fine finishing board used extensively in the building industry and primarily for trim work such as door lining, architraves, skirting boards, window boards and moulded doors.
While the finished surface of the boards are smooth, the edges and any areas where trimming has been carried out, the finished MDF is coarse with an open surface.
Applying water-based primers can lead to several problems:
- The surface of the MDF may have residual wax present, which would result in poor adhesion onto the surface
- Depending on the MDF grade, the water content in the water-based primers could be absorbed into the surface and lift the wood fibres causing a rough surface
- Water-based materials will penetrate into the edges and bare moulded areas, and will not provide a sealed surface for finishing coats.
Remedy
Prime all bare areas with an oil based primer. This can then be over-coated with either oil based undercoats and finishing coats or acrylic water based finishes.
For construction, other grades are available: Fire-resistant grade is colour coded Red and Moisture- resistant grade is colour coded Green.
Health and Safety
As the MDF fibres are very fine, wearing a face-mask during sanding or cutting is advisable.