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Guide to Painting Various Surfaces

Painting Masonry Surfaces

1. Potential Problems with Masonry Sealer

Masonry surfaces include brick and cement plaster. In some instances gypsum-based or skim coatings are also used.

These surfaces provide specific challenges for the painter:

  1. Most masonry surfaces are weak, friable porous and sandy.
  2. Cement plasters are seldom aged enough to allow the alkaline lime to neutralise with carbon dioxide from the air. The surface is alkaline a consequence.
  3. Moisture and damp are often present during and after application of paint. This can prevent good film formation as well as cause blistering in the dry paint. It is good practice to locate and remove all sources of water ingress into a structure before painting. A reputable waterproofing contractor should be capable of doing this. Promac Paints has a full range of waterproofing products.
    Contact Promac Paints for more information.
  4. Efflorescence can be a problem on bricks. This is due to water carrying soluble salts from within the brick to the surface.
  5. Fading and discolouration sometimes occurs when painting cement plaster as well as gypsum plaster. This is normally due to lime or alkali attack on the finishing coating the case of cement plaster primer as a barrier film between the plaster and the topcoat. On gypsum, a white patch often develops if the plaster is painted with a waterborne product before the gypsum has been adequately cured. The white effect is due to soluble sulphate being extracted into the wet paint. It tends to bleed through subsequent coatings as well. The solution is to ensure the plaster cures overnight before painting and that a sealer such as bonding liquid should be applied. This prevents extraction of soluble material into the finishing coat.

2. Standard Surface Preparation Method

This is the critical part of any painting project: poor preparation is the principal cause of coating failure.

Cement plaster should be strong and hard. If it is not, this indicates a poor sand/cement/water mixture. Painting over poor plaster will usually result in flaking, blistering and efflorescence defects-, which are not due to quality of the paint system.

  1. Brush off all loosely bound sand particles.
  2. Open out any cracks using a sharp knife.
  3. Seal all cracks or surface imperfections using promac bondseal. Leave to dry for 2 hours.
  4. Fill all cracks or surface imperfections using promac crack fix, leave to dry for 4 hours. Sand the surface till smooth.
  5. If surface is highly porous or friable, apply promac bond seal over the entire surface.

IMPORTANT

  1. Always use penetrating sealer such a spromac bondseal if the surface of the masonry (especially cement or gypsum) is friable. This will strengthen and reduce the possibility of coating failure.
  2. The use of Gypsum based and skim coatings are NOT recommended by promac paints. These materials have inadequate flexibility and wet strength and should not be used. Promac Paints recommends the use of promac crack fix for this application.
  3. For fibre-cement boards, or lower porosity surfaces, it is recommended that promac bondex ia applied in place of bondseal.

3. Primer Selection

A.
Top Coat: Enamel
Primer: Promac Plaster Primer – Alkali-resistant barrier to protect enamel system.
Undercoat: Promas universal undercoat aids overall coating integrity.

B.
Top Coat: Acrylic (waterborne)
Primer: Promac plaster primer – water-resistant barrier to protect acrylic system.
Undercoat: Promac GP – filler coat available in a range of textures smooth as well as rippled.

4. Finishing Coats

Use the highest quality that you can afford.

It is well known that the higher quality paints give the best durability and this, then results in the lowest cost in the long term. Promac paints has a full range of finishing coats ranging from matt to high sheen acrylics as well as enamels.

Painting Tiled Roofing

1. A guide to painting Roof Tiles

Roof tiles are usually mad from cement or (less commonly) clay. Cement tiles are prone o carbonation due to the effects of carbon dioxide and water in the atmosphere. This forms a very weak acid called carbonic acid that extracts the cement from the surface of the tiles and produces a weak, friable surface layer, which becomes more severe as the tile ages on the roof. Clay tiles do not have this problem, but they tend to be highly porous which can lead to poor curing of the paint film.

The most critical part of any painting project is the surface preparation, because poor preparation is the principal cause of coating failure. The object of surface preparation is to provide a strong, sound surface before applying any paint. Both types of tiles can be prepared in the same way. The first step is to thoroughly wash the surface using water and a strong brush. This should remove all loose bound sandy particles and any poorly adhering paint coatings. A high-pressure water jet is recommended for this purpose. The roof must then be rinsed with clean water and the left to dry out. The moisture content should be below 15% before any coating is applied. Measure this using a moisture meter.

The condition of the cleaned surface should now be checked: By pressing adhesive tape, such as masking tape firmly onto the dry surface quickly. Examine the underside of the tape. If no coating is removed and no dirt or chalky material is apparent on the underside of the tape, the surface is suitable for painting. It is also good practice to check the porosity of the surface before painting. Apply a droplet of water and note how quickly it absorbs into the surface. If it is readily absorbed into the tile, then the first coat of paint must be diluted 20% with water (for example, add five litres to a 20 litre container of pro-roof).

If a powdery layer is removed by the tape, the surface is chalky, and should be coated with Promac Bondex prior to applying the roof paint. It may not be possible to remove all sandy particles, but it is recommended to apply Promac Bond to seal any residual particles.

If the paint coating is removed, the surface under the coating is weak; strip the existing paint film and repeat the cleaning process. If Promac Bondex has been applied to the surface, it must be left to harden for at least two hours before continuing with any further application. Promac Pro-Roof is applied to the prepared surface using a roller (wool or Propile type), brush or by airless spraying. Two coats are recommended for optimum durability and the quality of the finish, but the first coat must be allowed to cure for at least two hours before applying the final coat. To calculate the amount of paint needed, one must estimate the plan area of the roof by measuring the length and breathe of the walls – multiply this area by 1.5 – and then estimate the paint quantity needed by dividing the estimated area by 7. This will produce a slight excess of paint, which is useful for touch up work, should this become necessary.

Pro-roof is a range of waterborne roof paints which is non-chalking, acid rainresistant and weather-resistant. It provides a tough, durable, medium sheen finish, and is available in all colours.

2. The Do’s and Don’ts to Obtain a Quality Finish

  1. Never apply paint if rain is forecast or expected during the day of application.
  2. Only apply paint after 08h00 in summer or 10h00 in winter, to ensure that the roof is not too cold or damp
  3. It is recommended that the paint is applied before 12h00 to avoid excessive roof temperatures and to allow the paint to harden sufficiently before any afternoon rain may occur.
  4. Always use the same batch number for touch up work. This reduces colour or sheen variations which otherwise may be visible on the painted roof. Promac Bondex is a unique, specially formulated penetrating sealer for chalky and less porous surfaces, it seals and binds chalky surfaces such as old paint coatings to allow painting with acrylic finishing coats.

Painting Gutters down pipes and Galvanized Roofing

1. A Guide to Painting Galvanized Roofs, Down Pipes and Gutters

What is galvanised iron? Galvanised iron is steel that has been dipped into molten zinc metal. This increases the corrosion resistance of the steel. The resulting material has a bright silver colour and is highly resistant to red rusting. Old galvanised iron may loose the protective zinc coating and red rusting may then occur. The surface of zinc metal oxidises rapidly to form a protective carbonate/oxide layer, which protects the zinc from further damage. This layer causes most paint failures because it can be relatively weak. This result’s in paint flaking .Zinc metal also inhibits the curing of enamel paints. This is the main cause of poor adhesion of enamels applied directly to galvanised iron without the correct primer. Waterborne acrylic paints such as Promac Pro-roof adhere well to clean galvanised iron and have superior exterior durability compared to enamels. However galvanised iron is prone to “white rusting” in humid or corrosive environments and a properly designed primer (e.g Promac Promogrip Galv Primer) is necessary for long term durability.

2. Surface Preparation

This is the critical part of any painting project: poor preparation is the principle cause of coating failure.

It is very important to remove surface dirt, grease and other contaminants as well as loose paint coatings and surface oxidation (e.g. dull, matt grey surfaces) in order to ensure optimum adhesion and durability of the paint system. The necessary steps are as follows:

  1. Wash the surface thoroughly using water and a strong brush. This should remove all loosely bound contaminants and any poorly adhering paint coatings. Use a spatula or flat blade to check adhesion of any existing paint coatings. A high pressure water jet is recommended.
  2. Apply Promac Grannozinc to any exposed metal. This dissolves surface oxidation and helps to remove any oily contamination. Leave in contact with the roof for five minutes maximum, and then rinse the roof with clean water, leave it to dry out. Apply the primer within two hours of cleaning to avoid possible recontamination of the surface.
  3. Check the adhesion of any existing paint coatings by pressing adhesive tape (e.g. masking tape) onto the dry surface. Pull the tape off the surface, inspect the underside of the tape if no coating is removed or no dirt or chalky material is on the tape the surface is suitable for painting. If a powdery layer is removed (painted surfaces only) or paint surface is chalky apply Promac Bondex. If sandy particles are removed or surface is dirty then re-wash the surface. If a paint coating is removed or the surface under the coating is weak then strip the paint film and repeat the process.
  4. Prime exposed metal using Promac Promogrip Primer (Galvanised) and cure for at least two hours before continuing. If red rusting is present, then Promac Uniprime is specified.

3. Calculating how much paint is needed

  1. Estimate the plan area of the roof by measuring the length and breath of the walls.
  2. Multiply this area by 1.25.
  3. Estimate the litres of paint needed by dividing the above by 7.
  4. One litre of paint will cover approximately 30m of 30mm radius downpipe of gutter. This should produce a slight excess of paint, which is useful for touch up work as required.

4. Paint Application

  1. IBR or corrugated roofing: Apply primer or Pro-Roof to the prepared surface using a roller (wool or “Propile type); brush or by airless spraying. Two coats are recommended for optimum durability and quality of finish. Allow the first coat to cure for at least two hours before applying the final coat.
  2. Gutters or Downpipes: Apply primer or Promac Pro-Roof to the prepared surface by brushing. A small foam roller (e.g. Vestron type) may also be used.

5. Other Important Information

  1. NEVER apply paint if rain is forecast or expected during the day of application.
  2. Only apply paint after 08h00 in summer or 10h00 in winter, to ensure that the roof is not too cold or damp
  3. It is recommended that the paint is applied before 12h00 to avoid excessive roof temperatures and to allow the paint to harden sufficiently before any afternoon rain may occur.
  4. Always use the SAME batch number for touch up work. This reduces colour or sheen variations which otherwise may be visible on the painted roof. Promac Bondex is a unique, specially formulated penetrating sealer for chalky and less porous surfaces, it seals and binds chalky surfaces such as old paint coatings to allow painting with acrylic finishing coats.

Painting Concrete Paving and Floors

1. Introduction to Painting Concrete Paving and Floors

Floor coatings are specially designed to tough and abrasion resistant.

Special properties such as acid and oil resistance may be required for certain floors, e.g. in garages and workshops. Cast in situ concrete is often used for driveway and other paving applications. This material is often not cured properly (i.e using impermeable membrane such as polythene cover) and subsequently the surface layers fail to cure adequately and a sandy; friable surface is produced.

2. Surface Preparation

This is the critical part of any painting project: poor preparation is the principal cause of coating failure. The object of the surface preparation is to provide a strong surface before applying any paint. The necessary steps are as follows:

1. Wash the surface thoroughly using water and a strong brush. This should remove all loosely bound particles and any poorly adhering paint coatings. A high pressure water jet is recommended.

2. Rinse the floor with clean water and then leave it to dry out. The moisture content should be below 15%. This can be measured using a moisture metre.

3. Check the adhesion of any existing paint coatings by pressing adhesive tape (e.g. masking tape) onto the dry surface. Pull the tape off the surface and inspect the underside of the tape.

  • No coating removed: no dirt or chalky material on tape surface: is suitable for painting
  • Powdery layer removed, Surface is chalky: apply Promac Bondex.
  • Sandy particles removed Surface is friable: rewash the surface.
  • Paint coating removed Surface uner the coating is weak: strip the paint film and repeat the cleaning process.

4. If Promac Bondex has been applied to the surface, leave it to harden for at least 2 hours before continuing.

3. Paint Application

  1. Acrylic Coating System:
    Apply promac Bondex to the surface, leave to cure for at least two hours, then apply Promac Allgaurd to the surface using a roller (wool or Propile type) brush or airless spraying. Two coats are recommended for optimum durability and quality to finish. Allow the first coat to cure for at least two hours before applying the final coat.
  2. Epoxy Coating System:
    Mix the two components (4 epoxy base + 1 hardener, by volume). Add 15% lacquer thinners. Apply to the surface using a brush or mohair (roller). Leave to cure overnight without diluting the paint. Note that this product has a pot life. If its consistency starts to thicken do not use the product.
  3. Enamel Coating System:
    Apply Promac plaster primer using a mohair (enamel) roller or brush. Leave to sure overnight then apply Promac Stoep Enamel using a mohair (enamel) roller brush.

4. Comparison of Coating Systems

Product Type Gloss Level Specific Properties Interior / Exterior Use
Allguard Acrylic
waterborne
Medium Sheen Exterior durability
Paving & Driveways
Both
Propox Epoxy enamel, twin pack High gloss Chemical & abrasion resistance Interior only
Stoep Enamel Stoep Enamel Polyurethane alkyd Semi-gloss Lower cost than epoxy resistant as
epoxy enamel
Interior/exterior
Shaded areas

5. Other Important Information

  1. NEVER apply paint if rain is forecast or expected during the day of application.
  2. Only apply paint after 08h00 in summer or 10h00 in winter, to ensure that the roof is not too cold or damp
  3. It is recommended that the paint is applied before 12h00 to avoid excessive roof temperatures and to allow the paint to harden sufficiently before any afternoon rain may occur.
  4. Always use the SAME batch number for touch up work. This reduces colour or sheen variations which otherwise may be visible on the painted roof. Promac Bondex is a unique, specially formulated penetrating sealer for chalky and less porous surfaces, it seals and binds chalky surfaces such as old paint coatings to allow painting with acrylic finishing coats.

Painting Wood with Varnish or Paint

1. Introduction

Wood has a natural beauty that is usually enhanced by the use of transparent coatings called varnishes.

Wood has to be protected from damage by water, sunlight and abrasion. There are various varnishes for different end – uses:

  1. Exterior Varnish Promac timberthane Available in Gloss, suede and colours. Conatins UV light absorbers and linseed oil for superior wood protection
  2. Interior Varnish Promac Coapl Varnish Available in gloss only
  3. Interior floor varnish Promac polygloss/polysilk Polyurethane modified for extra toughness. Excellent for floors and table and chair surfaces.
  4. Interior Floor solid colour Promac Stoep enamel Polyurethane modified for extra toughness
  5. Solid colour, int/ext Promac Prosilk Polyurethane modified non-drip semi gloss enamel Promac super gloss High gloss enael for interior/exterior use

Promac Walldex Medium sheen acrylic with excellent exterior durability Promac Provelvet High sheen with excellent exterior durability.

2. Surface Preparation

This is a critical part of any painting project: poor preparation is the principal cause of coating failure.

The object of surface preparation is to provide a strong surface before applying any paint. The necessary steps are as follows:

  1. Sand the surface using successively finer abrasive papers. Sand in the direction of grain, the use of a sanding sealer will improve the quality if the resultant finish.
  2. Remove dust from the surface by wiping with a damp cloth (not wet) lint free.

3. Paint Application

  1. Clear varnishes:
    Apply selected varnish to the surface, leave to cure overnight then lightly apply a second coat. Brushing is the preferred method. Further coats may be required over porous soft wood (e.g. SA Pine)
  2. Solid colour top coats (enamels):
    Apply promac wood primer by brush or roller. Leave to cure overnight, and then lightly sand the surface before applying promac universal undercoat. Then lightly sand the undercoat and dust off. Apply the selected enamel topcoat and leave to cure overnight. Apply a second coat of topcoat for optimum quality of appearance.
  3. Solid colour top coats (acrylic):
    Apply promac wood primer by brush or roller. Leave to cure overnight, and then lightly sand the surface before applying selected acrylic topcoat and leave to cure for at least four hours. Apply a second coat for optimum quality of appearance.

4. Other Important Information

  1. NEVER apply paint if rain is forecast or expected during the day of application.
  2. Only apply paint after 08h00 in summer or 10h00 in winter, to ensure that the roof is not too cold or damp
  3. It is recommended that the paint is applied before 12h00 to avoid excessive roof temperatures and to allow the paint to harden sufficiently before any afternoon rain may occur.
  4. Always use the SAME batch number for touch up work. This reduces colour or sheen variations which otherwise may be visible on the painted roof. Promac Bondex is a unique, specially formulated penetrating sealer for chalky and less porous surfaces, it seals and binds chalky surfaces such as old paint coatings to allow painting with acrylic finishing coats.

Waterproofing and Treating Damp

1. Principles of Waterproofing

The objective of waterproofing is to stop water entering a structure.

The best way to stop water ingress is good design: design for drainage to reduce the amount of water standing on a surface. Unfortunately buildings contain many flat, horizontal surfaces and also joints such as those between roof tiles and parapet walls, which can promote water entry. Cracking is masonry and leaking pipes are other problem areas.

Principles of damp-proofing

  1. Find the Water Source
  2. Insulate the water source (e.g. fix leaking taps and drains: apply waterproofing to parapet walls etc)
  3. Leave the surface to dry out below 15% moisture content.
  4. Remove old paint coatings down to sound bare plaster.
  5. Apply paint system (Promac Palster Primer and selected finish coats)

2. Waterproofing Systems

  1. Fabric reinforced acrylic (Promac Proseal)
    This utilises waterborne acrylic waterproofing impregnation of polyester non-woven fabric reinforcement. It allows complex shapes to be insulated. The fabric is a carrier of the acrylic waterproofing compound and the resultant effect is similar to canvas.
    a) Apply a thick coating of Promac Proseal to the clean prepared surface.
    b) Embed the fabric into the proseal while it is still wet. Press fabric down well and ensure no bubbles are formed.
    c) Apply a second coat of Proseal over the fabric, ensuring complete saturation of the fabric. Failure to do this, often results in blistering and poor waterproofing. Leave to dry, for at least four hours.
    d) Apply a third coat of Proseal and leave to dry for at least 4 hours. For optimum weather resistance, apply Promac Pro-Roof as a final coating.
  2. Fibre-reinforced mastic (Promac Fibreseal)
    This product contains special fibres that provide extra reinforcement and prevent the need for use of a reinforcing fabric. This product is applied as a thick layer by a towel to a clean, sound surface. Leave the product to cure overnight before applying weather resistant top coating (e.g. Pro roof, Walldex, Micaquartz etc. This product is excellent for waterproofing parapet walls and capping.
  3. Water-repelling Fluid (Promac Pro repel)
    This is a silicone based clear fluid that makes masonry surfaces water repelling. Liquid water does not wet treated surfaces and this prevents water entry into the surface. Water vapour can pass through the surface, therefore allowing the surface to dry out. The use of Pro Repell as a waterproof barrier under a paint system protects the coating system from water entering behind. This reduces the damp patch effect that can occur on some walls. Pro-Repell does not leave a varnish like film and is invisible. It does not bind friable or weak surfaces and does not function over gypsum or painted surfaces. Pro-Repell is ideal for treating face brick, ceramic tiles and concrete surfaces.

3. Surface Preparation

This is a critical part of any painting project: poor preparation is the principal cause of waterproofing failure.

The surface must be sound a free from dirt loose particles, oils etc.

  1. Brush off all loosely bound sand particles
  2. Open out any cracks using a sharp knife
  3. Seal all cracks or surface imperfections using Promac Bondseal. Leave it to dry for 2 hours.
  4. Fill cracks or surface imperfections using Promac crack fix. Leave it to dry, for 4 hours, sand the surface smooth.
  5. If surface is highly porous or friable, apply Promac Bondseal over the entire surface.

NB: This does not apply to the use of Pro Repell.

4. Other Important Information

  1. NEVER apply paint if rain is forecast or expected during the day of application.
  2. Only apply paint after 08h00 in summer or 10h00 in winter, to ensure that the roof is not too cold or damp
  3. It is recommended that the paint is applied before 12h00 to avoid excessive roof temperatures and to allow the paint to harden sufficiently before any afternoon rain may occur.
  4. Always use the SAME batch number for touch up work. This reduces colour or sheen variations which otherwise may be visible on the painted roof. Promac Bondex is a unique, specially formulated penetrating sealer for chalky and less porous surfaces, it seals and binds chalky surfaces such as old paint coatings to allow painting with acrylic finishing coats