Hints and Tips

May occur if solvent-based paints are overcoated with an emulsion paint in an area that suffers from condensation. It may be that the paint was applied in damp conditions.

Scrape back to a firm edge all loose paint. Lightly sand the surface. Spot prime bare areas with a Primer Sealer, and use an Acrylic Eggshell for painting.

The amount of water vapour that air can hold is limited. When this limit is reached the air is said to be saturated. Most condensation in buildings is caused by warm moist air coming in contact with cooler surfaces. In houses condensation is most likely to occur in kitchens and bathrooms. Some forms of heating generate large volumes of moisture vapour, paraffin stoves being the most notable.

Condensation is best prevented or controlled by providing good ventilation. Heating combined with good ventilation will reduce the problem. Special anti-condensation paints will provide short term relief, but painting alone will not cure the problem. Conditions within the building must be improved.

The development of small cracks on inside plaster walls and ceilings is not unusual and is normally the result of drying out (in the case of new houses) or movement of the building. Large cracks that appear to be getting wider should be investigated by a building surveyor.

If you are keen to undertake the work yourselves, this guide as to the sequence of operations may be helpful.

Sequence of operations before painting:

• Remove pictures, mirrors and light fittings.
• Remove small and light furniture.
  Place heavy & bulky furniture in centre of room.
• Cover floor and furniture with dust sheets.
• Remove curtains.
• Remove fittings.

Sequence of operations for preparation:

• All processes should commence at the highest point & work downwards. Wash, abrade and make good surfaces in the following order:
  • ceiling & cornice
  • frieze and dado
  • windows
  • doors & other woodwork.
• Remove rubbish from site.
• Spot prime bare patches.

Sequence of operations for painting:

• Working from top:
  • ceiling & cornice
  • frieze & dado
  • windows
  • doors
  • other woodwork, completing with skirting board.

Sequence of operations before hanging surface coverings:

• Prepare as for interior painting.
• Undercoat as for interior painting, omitting surfaces to be papered.
• Size and cross-line if necessary.
• Complete painting as for Interior Painting, taking paint 6mm on to lining paper at cornice, architraves and skirting.

Where damp is a problem it may be due to a defective or missing DPC, broken or defective rainwater pipes and gutters, defective pointing in brickwork, unsuitable cladding, solid wall construction or other general building defects. The source of the dampness should be found and cured. The surface must be allowed to completely dry before painting. A shellac based sealer can then be applied prior to overpainting in the finish required.

Efflorescence is caused by the crystallisation of salts found in building materials such as bricks. Remove fluffy efflorescence deposits with a coarse hessian sacking. Repeat the process every few days until no more appears. It is best not to use solvent based paints on new buildings for at least a year, as the substrate must be dry in depth.

Flaking/blistering of paint on wood is most commonly caused by moisture beneath the paint film. Knots in the timber can also lead to blistering. Flaking can occur if paint has been applied over denatured wood, dirt, grease, etc. Movement of the wood, particularly on joints can cause it to crack. This can allow moisture to penetrate the wood which in time can lead to flaking.

Areas of flaking or blistering paint should be removed by scraping back to a firm edge using a paint scraper. Sand down to smooth edges. If the problem is extensive the surface should be stripped back to bare wood. All knots streaks should be treated Knotting Solution and then bare wood should be primed. Make good all open joints and surface with suitable wood filler.

A useful little aid to help you arrive at the right number of rolls for wallpapering is the interactive "How Much Do I Need" calculation tool.

The term "microporous" is often applied to specialist paints and stains for exterior wood: to describe a coating that acts as a barrier to liquid water, but allows water vapour to pass through. It is not correct to imply that coatings can be made so that moisture vapour can only travel through them in one direction. This is a complex subject - send us an email using our contact form and we will be happy to provide you with information.

Wood finishes can be divided into four main groups:

1. Preservative
   Colours and preserves new or weathered sawn timber. Cannot be applied over any film build coatings i.e. all the other wood finish categories listed below.
2. Paints
   High build coatings which obliterate the underlying surface i.e. they are opaque.
3. Varnishes
   High build coatings through which the underlying surface can be seen i.e. they are transparent.
4. Woodstains
   Can be low to high build coatings which are either semitransparent i.e. they are coloured but allow the underlying surface to be seen or they can be opaque, obliterating the surface.

WOODSTAINS - IMPORTANT POINTS TO NOTE:

• The final colour is very dependant on build (film thickness), number of coats and the underlying surface colour and texture.
• Repeated decoration with the same colour of woodstain will eventually darken the colour.
• When redecorating dark colours, it is often advisable to chose a light colour for protection of the surface without changing the colour too much. Knots in timber must be treated with knotting when applying paint or opaque woodstain.
• White (bleached) knotting must be used with water based coatings. Where fillers have been used, colour will vary with the surrounding timber.

The ability to breathe is vital to the survival of almost all historic buildings and the application of impermeable modern renders and coatings must be avoided at all costs. Send us an email using our contact form and we will be happy to provide you with information.