Steam Washing/Cleaning wood (mainly) before painting

RHemmings

I have two things that I wish to paint/stain. 

The fence on one side of my garden has never been painted or stained. I would like to use 'Ronseal' on it, but there's green algae(ish) on it. I'm thinking that steam washing would handle this without damaging the wood. 

Also, I have wooden decking which I believe has been painted with something unsuitable and it's coming off. I'd like to repaint that, but feel that I should at least steam wash. 

I haven't done this sort of thing before, and don't have the equipment. 

Could people please advise: what sort of washing/preparation would be best. And, what sort of equipment I'd need to do that. The choices are to buy or hire equipment. The cost and size (for storage) of equipment will affect the latter choice. 

Any advice would be greatly appreciated. 

EDIT: Not a steam washer, but a power washer? https://www.toolstation.com/karcher-k4-universal-pressure-washer/p42670

EDIT: Apparently there is a cleaning fluid called 'outdoor cleaner', which can be sprayed on, brushed off, and cleaned with a hose. https://www.youtube.com/watch?v=B2wEoHYHCx0

CliveOfIndia

I've done exactly this myself many times over the years.  Give it a blasting with a pressure washer, give it time to dry out properly, then on with the paint/stain/whatever.  It's simple to do and has always worked well in my experience.

The only thing to watch for is that the pressure washer can roughen-up the wood sometimes.  I guess it depends on what type of wood it is, but it's always seemed to be more noticeable on my deck than the fence.  Nothing that a quick going-over with coarse sandpaper doesn't fix, and you only need to get the worst of the splinters off to make it more comfortable to walk on in bare feet.

But overall, a pressure washer does make the job very quick and easy.  If you're looking to buy one, shop around.  You'll find there are a huge range of models and a huge price-range.  But if it's not going to be used very heavily, a cheap own-brand one from Screwfix, B&Q etc., or online, will do the job.

Albermarle

But overall, a pressure washer does make the job very quick and easy.  If you're looking to buy one, shop around.  You'll find there are a huge range of models and a huge price-range.  But if it's not going to be used very heavily, a cheap own-brand one from Screwfix, B&Q etc., or online, will do the job.

Just do not leave them outside/in a shed in the winter, regardless if they are a cheap one or not. If there is a hard frost it damages them and the guarantee is invalid .

RHemmings

Thanks very much @CliveOfIndia and @Albermarle.

This is another of the things that I've never really thought about before, given that I've always rented until this year. 

Looking at your replies, I'm a bit concerned about roughing up the wood. Of both the decking and the fence. And, while the fence isn't those cheapest possible panels that are quite common, it's not really big chunks of solid wood. 

I'm a bit tempted to give the: spray cleaner on, give it a good brush, and then hose off approach a go first. 

On the other hand, I have a Toolstation down the road from me, and I could just buy one of these: https://www.toolstation.com/hawksmoor-high-pressure-washer/p44787  The reviews seem good for the price. It says max 1400W, which I presume means that it can be set lower depending on what is being washed. It doesn't come with a patio cleaner, but I note photos of someone using on a patio. 

BTW: I never keep electrical stuff outside. But, I will admit that the space under the stairs where that sort of thing goes is getting a bit full. If I owned one of these pressure washers, does that mean that my bicycles will start getting washed for the first time in their lives? 

CliveOfIndia

RHemmings said:

It says max 1400W, which I presume means that it can be set lower depending on what is being washed.

With pressure washers there's really two things that determine the highest pressure it can deliver - the power of the motor and the water flow-rate.  A higher-powered motor coupled with a high water flow-rate will give a much more powerful jet.  But to be honest, an awful lot of the domestic machines are much of a muchness.  Yes, some will be a bit more powerful than others, but there's little in it for most practical purposes.

In terms of adjusting the power, that's usually down to the spray pattern, as well as how close you hold the lance to the thing you're cleaning.  A thin pencil-jet held really close to the object will blast through anything, but would take ages to clean a large area (but ideal for removing really stubborn stuff like dried-on chewing gum, paint, that sort of thing).  Conversely, a wide jet held a foot or so away from the surface is great for rinsing things off, but won't shift anything more than the lightest bits of dirt.

It's all about trial and error.  Any machine will come with either an adjustable spray head or a variety of different spray heads, giving you the option of a narrow high-power jet or a wider low-power jet.

Just be careful about using the very high-power jet on cars and bikes.  Some of them can be powerful enough to quite easily damage paintwork, trim, that sort of thing.

And hopefully it goes without saying, but never ever be tempted to muck about and spray it at a person or an animal.  Even quite a low-powered jet has the potential to cause a nasty injury, especially if it's pointed at someone's eye.

Albermarle

Good advice above but not sure about the first part, although I might have misunderstood what you meant,
With pressure washers there's really two things that determine the highest pressure it can deliver - the power of the motor and the water flow-rate

AIUI, the flow rate from the jet sprayer is normally less than the normal flow rate into the jet sprayer ( from the tap/hosepipe) so the flow rate from your tap will not affect the jet spray ( unless the flow was abnormally low) .

It doesn't come with a patio cleaner, but I note photos of someone using on a patio. 

In the past I had one without a patio cleaner and it was a few hours work to clean all the patio and paths. With a patio cleaner it takes less than an hour, and then maybe another 20 mins with the jet to wash the crud away and clean any bits I missed. 

CliveOfIndia

Albermarle said:

Good advice above but not sure about the first part, although I might have misunderstood what you meant,
With pressure washers there's really two things that determine the highest pressure it can deliver - the power of the motor and the water flow-rate

AIUI, the flow rate from the jet sprayer is normally less than the normal flow rate into the jet sprayer ( from the tap/hosepipe) so the flow rate from your tap will not affect the jet spray ( unless the flow was abnormally low)

Sorry, what I meant was the output flow rate.  So one that pumps out 500 litres per hour will perform better than one that puts out 300 litres per hour, all other things being equal.  Which is one reason why they're always advertised as "so many KW motor" and "so many litres per hour".

I guess if you're on a water meter then you might prefer a lower flow rate !

BarelySentientAI

Albermarle said:

It doesn't come with a patio cleaner, but I note photos of someone using on a patio. 

In the past I had one without a patio cleaner and it was a few hours work to clean all the patio and paths. With a patio cleaner it takes less than an hour, and then maybe another 20 mins with the jet to wash the crud away and clean any bits I missed. 

I could never make the patio cleaner attachment for my Nilfisk work very well at all, so always resorted back to the standard lance.