Soft washing. What is it? How does it work?
Soft washing is a cleaning process. It uses low pressure and chemicals to remove mould, algae and organic growth from exterior surfaces.
Commonly used on walls, roofs and render, it is a gentler approach to cleaning. On delicate surfaces like render or roofing, soft washing is a preferred choice over high pressure. There is a much lower risk of damage because there is no high pressure water used. As with any cleaning methods, there are downsides.
Over the years the soft washing scene has become favoured by many companies. It’s fast, in fact soft washing has become a bit of a buzz word in the cleaning industry. The problem is, cleaning of walls, soffits and facia boards is all well and good. Driveways and patios tend to suffer with dirt and grime a lot more than their vertical counter parts.
So what exactly is soft washing?
By mixing a chemical with water and a surfactant you can create a cleaning recipe. The mix of chemical to water depends on the surface and level of organic growth.
Dosing Unit
Soft washing recipes vary from a low 1% diluted solution to around 7.5% diluted solution. The chemical used is sodium hypochlorite, or swimming pool chlorine. It has a typical strength of around 14/15%, which is about 4.5x stronger than household bleach. Diluting the chemical alters the strength, with 1% being 1:14 and 7.5% at 1:1. Yet sodium hypochlorite is thin like water, its sprayed onto surfaces. Adding a surfactant to the mix creates a foam which can help it cling.
How does it work?
Once the dilution ratio’s known, it’s applied. Generally it’s sprayed, either by pump sprayer or a dedicated application dosing unit. The entire surface gets saturated with the solution and left to work for around 20mins. After this time it’s rinsed off. No agitation’s required, the chemical does the work. This is the reason a lot of companies love this method, it’s fast and requires very little physical work. But, the best result is always in the prep.
Soft washing driveways & patios
In our eyes the soft washing of driveways and patios is a bit of a short cut. Applying a chemical can help transform an area pretty fast, but it won’t remove weeds or moss. If used strong enough can help kill off any weeds, but as a customer you want a fresh clean area straight away.
The use of soft washing has its place don’t get me wrong, but a jet wash will always win on the final finish. If the area is in poor condition, the mortar joints broken or it’s cracked. This is where soft washing can give you a cleaner area but without any extra damage. There is nothing worse than having massive open, broken joints to look at. Before they had dirt and moss, now it’s been jet washed it looks like a grenade had gone off on your patio. By soft washing it will clean the stone but won’t affect the joints.
We utilise this style of chemical cleaning alongside our jet wash, this is what we call our deep clean. Sodium hypochlorite is an awesome cleaner. But one major drawback is that it reacts with the first thing it comes into contact with. If the area is super dirty, the chemical has a lot harder work to do. A good result even with a 1:1 mix without pre jet washing is hard to achieve. By pre washing you will remove as much of the dirt as possible. This gives the chemical more chance to work on the stubborn areas.
Other drawbacks
Over the years we have heard many stories. If we had a pound for every time somebody says “soft wash it mate” I could retire. If we learn anything from life it’s that things cannot be rushed. How are you to build a professional image by earning a quick buck. Nothing done right is quick. Time and hard work pay off in the long run. At the end of the day as a customer you want to feel like you have received something for your money. If getting the best finish in 20mins was possible, everyone would be trying it.
We have seen pictures of block paved driveways, only soft washed. Yes, the blocks are pretty clean, but are you paying for clean blocks outlined with weeds and dirt, no. The only way to shift all that muck is with a pressure washer, not soft washing.
The strength mix of the chemical can also have an effect on plants and grass. Make sure whoever is doing it knows what they are doing and have advised you on possible run off.
Can we soft wash?
We specialise in driveways, patios and decking. The soft washing of roofs is not something we do. Can we soft wash your patio or driveway, sure. We prefer to use our jet wash but if soft washing is something you would prefer we can do that.
What won’t soft washing do?
Soft washing doesn’t tend to remove lichen spores (black spots). In fact it will struggle with most forms of lichen including white. Since white lichen is crusty, it requires the use of high pressure to remove. Soft washing has very little effect on lichen, unless it’s quite fresh. Black spot lichen is a rooting spore and beds itself deep into stonework. We can remove white lichen with our washer. Black spot lichen is removable but requires a much stronger dose of chemical. If you have black lichen have a look at our dedicated page here.
If you want to see our machine removing heavy white lichen, have a look at our YouTube video. White lichen removal