Why Remove Paint?
The removal of paint from a masonry surface should not be considered as simply a cosmetic procedure, it can also significantly affect a substrates condition and increase the length of its life...
Use of Paint - Historical Context
As expected coatings will also have been applied retrospectively to hide staining, soiling, or deterioration, as well as for later aeshetic trends. Whilst the choice of coating may be entirely compatible with the substrate, this or later coatings may not. The incompatibility may lead to premature failure of the substrate, or of the coating (and usually both). These and other factors will affect the decision making process, over the removal of old and the choice of replacement coatings.
Historic structures, are likely to have any combination of paints applied to a number of different substrates such as stone, brick, terracotta, timber etc. For any of these older types of buildings, to actually remove paint coatings safely and effectively, the utilisation of a number of methods is not uncommon. Whether the decision to remove paint has been made on cosmetic grounds, or as is often the case, to arrest deterioration of the substrate - it is important that the best methods are utilised 'case by case'.
Considerations for Removal
The process of paint removal can rarely be regarded in isolation. This may be undertaken as part of a larger project of refurbishment, in which case the timing must be planned and not regarded as an afterthought. It is frequently desirable to undertake removal as the first objective, to highlight defective areas of masonry and before the replacement of windows, timbers, redecoration etc. Whichever method of removal is appropriate, it should be bourne in mind that it will often be disruptive to other trades, who may also be on site and can be a potential source of conflict.
There are many different reasons as to why paint should be considered for removal, as in the following cases;
In some urban areas, where serious atmospheric pollutions are present for instance, an ordinary paint coating may have been applied to try and disguise any thick carbon pollutants that were detracting from the buildings visual appearance - Although this is no longer common nowadays, there are still numerous examples of this practice visible in many towns and cities around the country.
Some of the paint coatings which were designed and applied during the sixties and seventies, worked on the principle of 'complete' removal of vapour permeability. They principally worked on completely sealing the building from external weathering etc. The opposite has normally proved the case as these coatings have often gone on to accelerate, damage and even shorten the life of a building to which it was meant to protect, by preventing it from breathing. Any trapped moisture even in small degrees can have potential serious consequences, allowing damaging moulds to develop, or allowing trapped salts to cause deterioration to the walls themselves etc.
A basic requirement for repainting is a sound surface on which to apply. Simple washing, perhaps with a biocide, may suffice but is more often not the case. Ingress of water from failure of the old coating or more usually through deficiencies of the roof, guttering and dam course will need to be addressed. The demand for a damp structure to breathe is a lesson that has had to be relearned after decades of neglect and misunderstanding. Water is the catalyst for chemical and biological reactions, the primary source of a substrate failure. The primary purpose of paint removal will often be to expose a surface or traditional coating on which can be applied a compatible paint. One inappropriate layer may be enough to perpetuate a problem. Whilst an inherently dry structure normally presents much easier choices, a modern coating may prove an unsatisfactory surface on which to apply an historically accurate one, e.g. limewash. Consecutive coatings will have obscured surface detail. Removal of such paints from a sound surface may still therefore, be desirable.
A reciprocal problem of paint removal is that before the extent and depth can be established the condition of the structure and substrate must be known and vice versa. This is where the experience of a specialist can help short circuit the cycle.
So, a judgment is made as to the extent of remedials, the choice of replacement coating and its compatibility with existing surface or overlay. The best 'tool' that can now be adopted, is the use of representative test panels. 'Representative' will mean more than one and at variations of height, elevation (north, east facing etc.) and substrate. Structural alterations or repairs, surfaces adjacent to entrances, or any other potential source of variation should also be tested. Not to employ test panels is likely to be false economy, particularly when employing a contractor. A contractor who knows what they are doing will also be aware of the pitfalls and will load the price accordingly to cover 'contingencies'. This should not be regarded as underhand but as understandable practice. Test panels are the 'proof of the pudding' and provide data for substrate condition and method, cost and timescale of paint removal. The assumptions made prior to the panels having now been tested, may now result in revision of the method and objective.
Prior planning will now ensure that once the work is underway, it will proceed in a logical methodical manner. Protection for adjacent fabric, plant life, pedestrians and numerous other impediments will have been provided together with means to contain the waste products of removal, be they liquid or solid. As a general rule work will commence at the uppermost level and proceed downward, to maximise protection of cleaned areas and to allow repairs or redecoration to commence above, if necessary. The scale of the project will obviously dictate the importance or otherwise of these considerations.
Seeking Professional Advice for Suitability & Costs
For owners of listed properties, it is important that the local Conservation Officer should be consulted prior to any commencement of any work, not least because listed building consent may be required. Whilst they may not be in a position to say what you should do, they will be able to advise on what you cannot. This position is actually a positive one, as they cannot be expected to be a paint removal consultant and supervise work on behalf of an individual, but they will normally do their best to provide sources of information. Depending on the status of the building other sources of guidance and advice are, for instance; SPAB, The Victorian Society & English Heritage.
It will therefore be necessary to establish a plan and to test certain key assumptions, to minimise the potential pitfalls. The engagement of a specialist consultant can be particularly useful at this stage. They will be able to advise as to whether the masonry was painted as an original finish and if so, of what type is appropriate. Certain paint removal projects, particularly domestic houses, are often in close proximity to plants and shrubs, to avoid destruction of plant life and long term contamination of the soil, their knowledge and advice will prove most valuable for example. Such experience will also take into account the permanent and possible detrimental effect upon substrate, that can happen with certain of the methods that are available, which without their thorough removal, some products have the ability to cause rapid failure, of later paint coatings.
The kind of questions that should be considered prior to the commencement of work, all of which will affect the level and cost of the process;
- Can the paint be removed without damage to the substrate?
- Do all the layers need to be removed?
- Can the work be carried out within budget and in the permitted time scale?
- Must access be maintained into, or past the building?
- Is the coating causing substrate deterioration - If so, is this isolated?
- If redecorating, what are the requirements for the new coating?
- If the decision is made to leave the substrate exposed:
- Is the substrate / structure up to weathering?
- Is this historically appropriate?
- Will exposure reveal disfiguring repairs / defects?
- Will the substrate require attention or restoration?
The answers to some questions will be straightforward, others will require detailed examination of the building and the implementation of test panels. |
