Self Build - The Finishing Touch

SELF BUILD - The Finishing Touch

Self Build can be the most rewarding, exciting, yet stressful, tear your hair out project you are likely to undertake. From experience it takes a lot of time and effort and will certainty have as many low points as highs, yet when the home is complete it is sure to give you a feeling of great achievement.

One of the last tasks but one that defines the enduring look of quality of your home will be the paint finish you choose. We often find that when approached by the owner other than knowing painting and decorating is required they are not sure where to begin.

An idea seems to persist that a cheaper lower quality paint is fine for first coating, but we suggest this may not be the best way in the long term, if you want the walls and doors to enhance your carefully chosen furniture and accessories. 

Here we will look at the alternatives we recommend for first coating newly plastered or skimmed walls.

Preparation is the Key - that adage is our starting point, so it is good to give the walls a light sanding, enough to remove any little splattering of skim or other imperfections that may be present. It may also be necessary to use a good filler like Toupret Redlite where any holes or surface indentations are present, again these filled areas will require sanding to a smooth surface. (Please always check where the fillers can be used to ensure it is suitable for the location, size and depth of hole you need to fill.)

The first method we discuss with our customer is the use of a water based emulsion for first coating, our Macpherson Eclipsepreference is Macpherson Eclipse but similar products are available from other manufacturers. 

An absolutely critical point in applying a water based emulsion unto new walls is to make sure that the paint is ‘watered down’ by around 30%. This simply means adding about 30% volume of water to the emulsion paint and combine the two together by giving it a good stirring.

The reason for this is to allow the paint to flow freely into all the little pores in the skim which are there even though the wall may look as smooth as glass to the naked eye. When the paint dries it is infused into the upper layers of skim and thus provides the required adhesion for the final layers of paintwork. 

CAUTION. If water based paint is put on full strength rather than soaking into the plaster it simply forms a dried layer on top of the substrate and you could end up with all the paint layers flaking or peeling right back to the bare wall. It is possible for this to occur long after decorating has been completed and may only become evident when redecorating takes place as a result of the weight and wetness of the new paint being applied. In fact we have had customers who have purchased a previously lived in home, redecorated and cant understand why this is happening

When this first coat has dried you are now ready to overcoat, and we suggest two coats of the finishing paint according to your choice of colour and sheen eg matt, soft sheen, silk.

TIP  When first coating with a water based emulsion look out for a particular effect where under certain conditions your paint will seem to ‘slide’ over certain areas of the wall forming a random pattern of largely uncoated surface. Trying to over paint with another coat of the water based emulsion usually makes the effect worse because you build up the coat on the unaffected areas and leave the problem surface in the same undercoated condition.

This arises when Alkaline solutions are present in the rubbed up substrate and react with the paint being applied (saponification)

If you find this is happening it is best to coat the affected wall with an alkali resisting primer, sealing in the area (after allowing the wall to dry out if it is an oil based primer you are using)

The second method we recommend is in fact to use an alkali resisting primer- Crown Trade Alkali Resisting Sealer or similar - as the first coat, in this case it is important your walls have had sufficient time for the Crown Trade Alkali Resisting Sealermoisture in the new plaster and skim to dry off - you could be looking at a number of months depending on the conditions at the time, whether you as heating the house and of course the weather.

An alkali resisting primer will seal everything in when it has time to cure on the wall surface. If you opt for an oil based alkali resisting primer you may find it more difficult to apply than a water based emulsion, but it can be thinned down with white spirit to ease the flow, but thinning should be kept to the minimum required.

A water based alkali resisting primer should be thinned with around 20% water before applying onto unpainted plaster or skim. Alkali resisting primers provide an ideal base for your final coats and should result in a superior finish.

Both oil and water based alkali resisting primers can be over painted with standard water based paints in the colour and sheen of your choice the same as with a water based emulsion first coat.

However bear in mind that an alkali priming system may cost more than three times as much per litre of paint than a good water based emulsion.

From time to time we also supply on request a PVA bond, this works in the same manner an alkali resisting primer in that its seals the surface that it is applied to, and again can be over coated with any kind of paint, but we do tend to stick to the first two methods.

With your first coat on and dried you are now ready to concentrate on the colours and sheen's that will help create the look and ambience you are after.


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