Features & reviews
Any colour but yellow
The yellowing of trim paints is a common problem for decorators, and one that features highly on home buyers' snagging lists. With so much confusion surrounding this issue, we've provided all you need to know about why this happens and how to select the right product for your job.
So why do some paints yellow?
Following changes in Volatile Organic Compound (VOC) legislation, paint manufacturers have been required to reduce the amount of solvent in traditional trim products.
As part of this process, many solvent-based coatings were reformulated to have a higher 'solids' content.
While these are better for the environment, thenew formulationscan discolour more quickly.This results in greater yellowing appearing on the paint surface in all conditions.Also, in environments with limited or no daylight, and highertemperaturesthe paints are prone to yellowing even faster.
Unfortunately, this discolouration is a challenge faced by all manufacturers and brands with solvent-based paints.
Is there a way around this?
Unfortunately not with solvent-based products.However, Dulux Trade has recognised this problem and invested heavily in exploring alternative formulations - in particular, the use of water-based paints.
Traditionally there has been some negativity toward water-based products, with decorators arguing that the earlier versions of these paintsdidn't deliver the high quality of finish required. However, paint manufacturers have focused on improving these solutions and there are now water-based solutions available which offer as good, if not better quality, than previous solvent-based paint.
The art is in the application
In order to achieve the best possible results, it is important to understand the differences between solvent-based and water-based solutions before application.
Water-based variants dry faster than solvent variants, with these coatings typically taking around four to six hours. It is best if water-based paints aren't applied if the temperature is below 10°C or humidity is over 80 per cent. In lower temperatures in particular, waterborne paints are slower in drying as they rely on the evaporation rate of water, which is lower at these temperatures.
As they are heavier in consistency, water-based paint may also clog if applied with a dry synthetic brush. Dampening the brush before application prevents clogging and avoids brush marks. Similarly with the gloss top coat, this issue can be overcome by lightly wetting the surface with a wrung out sponge before application.
Solvent-based paints traditionally have a smoother flow, meaning that brush marks flow out more easily. Water-based trim paints however, should be applied more heavily and then spread out. Another difference is in laying off. Rather than waiting after the first application, appliers should apply, lay off, then leave to dry.
By understanding the differences between solvent and water borne paints, and ensuring these simple principles are adopted during application, the benefits can be maximised. In turn, this helps ensure the trim areas of a property are completed to the long lasting, high quality finish that clients and potential purchasers expect.
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Comments (2)
adam f April 15th 2011
is the long term plan to faze out solvent based paints? and if not will they be more work done to stop the paint yellowing?
and will they be demonstrations in DDC stores to show off the water based gloss?
i use the water based gloss, i use the water based undercoat as standard, but can the water based gloss live up to the same standard of oil based gloss?
Rob G November 15th 2011
Hi Adam
according to Dulux, the new white gloss formula that they have brought out in recent months, is now better then the formula prior to the VOC regulations (2007). therefore we should stop seeing such a rapid yellowing from their solvent-based products.
Paint companies will not phase out oil based paints and if anything, they are only now set to improve us technology in this market becomes better. This is with exception of solvent-based paints for walls and ceilings(i.e- eggshell for walls), as the government has set unrealistic VOCs levels on these products but currently cannot be made at the moment.
In answer to your questionâcan water-based gloss live up to the same standard as oil based gloss? the answer is simply no. Waterborne paints will never have the same machine level as its oil based equivalent, and it will always (even with the best of brushes) leave brush marks as it is unable to flatten as good as a solvent-based product.
hope that helps, Rob