Lime wash on beams or ping Anna Kettle:-)

[Tim Lamb]

I am *still* renovating a Victorian timber barn. When it was used as a dairy for milking cows hygiene regulations required that the interior was finished in white. As a consequence there is a generation or two of flaky white lime attached to the beams.

I horrified the Architect by mentioning grit blasting. He strongly advocates using a wire brush!

I tried a well worn semi-cup brush at low speed in the ...wait for it.... angle grinder and was rather disappointed with the result. Soft patches are still excavated, grain is still raised and there was some evidence of blackening where I paused for too long.

Is there a best wire wheel type for this job? Presumably radial fine wire rather than stiff wire cup?

Speed is also at issue. I would be surprised if the grit blaster could not do the job in a long day (ground floor only 5mx10m) whereas wire brushing might take a week or two!

The down side to grit blasting is the tendency to strip areas weakened by woodworm, gouge holes where nails have been removed and leave sand embedded in the wood which falls out over the next ten years.

Any advice?

regards

[RubberBiker]

AIUI there are now specialist vapour blasting processes for this sort of problem.

Found this:

[The Natural Philosopher]

Try a GOOD and high power pressure washer

[meow2222]

A wire brush in a drill would be more appropriate. A nylon brush in a drill might be even better. You can also get nylon mesh wheels for use in a drill. Grit blasting does a lot of damage, its really not suitable I'd be very tempted by the pressure washer suggestion, no experience of that though

NT

[Andy Dingley]

Neither are much good - they both have a cutting rate that depends on material hardness, but doesn't care much about surface depth. They'll both accentuate any texture or rot that's present.

I'd actually suggest (bizarre though it sounds) a belt sander with a wide platen. This will tend to flatten variations, not highlight it. Of course the risk with these is that they're horribly sensitive to operator error and they'll dig in like crazy if you tilt forwards away from the platen and onto the roller. They're a lot better if you use them with a "sanding frame" attached around them, which stops this tipping.

Makita used to do a gadget that was a 6" wide flap brush, with swappable brushes from sandpaper shreds to wire. These were good for cleaing beams, so long as you didn't press too hard and the beams were reasonably consistent. Using the tips of the bristles gave a flat finish, pushing hard gave the hardness-dependent behaviour of a small brush. Cost hundreds though, I used to hire mine. Think Axminster used to stock them.

[John Rumm]

Yup, I have seen these used quite effectively... something like:

[Anna Kettle]

Hi Tim

Hi Tim

Whenever I have had to clean off flaky lime, I have been getting ready to relimewash. Is that an option in your case? Or could you go for the 'limed oak' effect? Because if so you dont need to get every last bit of lime off, just the loose bits and a stiff brush works just fine to do that

Otherwise ...

As TNP suggests, If you have a pressure washer and dont mind the barn getting wet then I'd be tempted to experiment with a pressure washer in an inconspicuous spot

or

As rubber biker says, there are various air abrasive systems and that is what the pros would use. Joss and Doff (sp?) are names that come to mind. I have never used them but those who have done say they are effective but there is a technique to using them. Presumably the hire people would tell you how

I dont like the sanding ideas. Sanding removes the surface of the timber and hence the patination and reveals woodworm holes which are not very pretty

I dont like the wire brush idea either, too much like hard work and will tend to abrade the surface rather than remove recessed limewash. But if you do use a wire brush then make sure it is brass not steel or you will be left with a fine scattering of rust on the timbers

Anna

[Tim Lamb]

In message , RubberBiker writes

blaster man can do that. I guess seeing what you are doing indoors is a problem as these guys wear something akin to a deep sea divers helmet.

regards

[Tim Lamb]

I'm not sure that my little Draper job reaches the GOOD category but I have got some lime washed studwork scrap which I can practice on.

My carpenter tenant has been rebuilding a steam cleaner which may give good pressures run cold.

regards

[Tim Lamb]

the idea of dust control.

regards

[Tim Lamb]

In message , Anna Kettle writes

Limed softwood in my case. There is very little Oak in the building but I think one section of eaves beam is Hornbeam! It does not have to be perfect but the ultimate use might be office accommodation so a drizzle of lime flakes worth avoiding.

I'll give this a try.

Luckily there is a contractor with a mobile set nearby.

Right. Paint scraper?

Yes. And discoloured Oak if there were any. There is no immediate hurry for a solution as the quotes for a building job I had hoped to unload to professional builders are coming back at what are known locally as

*Harpenden* prices:-(

regards