Monday, 2 November 2015

Olivine blasting - it's the future!

Q: Take a man on a mission, 7 bar of pressure, a quarter ton of (Mg+2, Fe+2)2SiO4half a dozen cups of tea, one trip to Pizza Hut and 12 hours of hard graft and what do you get?

A: Complete sensory deprivation, hundreds of dead flies, a huge mess, a very late night, massive changes at The Lodge and two very happy homeowners.

It all started a few weeks ago when I went to visit my parents for a few days.
Rather than sit through another 2006 re-run of Bargain Hunt on telly I turned to Google for my entertainment and started searching for info about sandblasting. That's what renovating a house does to your 'spare' time.

The Living Room fireplace was a mess of soot,
paint and gypsum plaster residue
We had known for a while that we wanted quite a lot of bare brickwork inside The Lodge so we could make features of some of the walls and three of the four chimney breasts (we can't reach the fourth yet because the Dining Room is being used as storage), but removing layers of thick plaster had left the bricks damaged and very messy. As well as that the Living Room fireplace had large patchy layers of lead paint where various decorators had plied their trade over the generations.
I had already made an attempt to clean the walls with brick acid and elbow grease but it was slow, less-than-perfect progress and it quickly became obvious that I was fighting a losing battle on both the plaster residue and paintwork. Drastic action - up to and including napalm - was required.

The term 'sandblasting', as it turns out, doesn't usually refer to the media of sand these days and is instead used as a catch-all for 'abrasive blasting'. In basic terms that means taking your material of choice and shooting it at high velocity at whatever surface you want roughened, smoothed, stripped or, as in our case, cleaned.

Surprisingly there are a lot of unexpected materials that can be used for blasting so for educational purposes here's a short list:

  • Glass
  • Plastic beads
  • Silicon carbide
  • Dry ice
  • Steel shot
  • Ground possum teeth
  • Pumice
  • Walnut shells
  • Olivine
  • Flash-dried unicorn tears
  • Corn cob

Disclaimer - two of those are made-up.

The problem we faced at The Lodge was that our bricks, being made of less-stern stuff than more modern ones, are naturally soft and crumbly which ruled out pretty much everything we could chuck at it. Steel shot, for instance, would easily clear away the paint and plaster, some of which was many millimeters thick, but where it touched the bare brick it would very quickly eat away the surface and make a right mess of the walls that we eventually wanted to show off.

Heston Blumenpillock
So after much searching and many YouTube videos I finally decided that dry ice blasting was worthy of a punt.
Everyone knows about dry ice - it's the misty stuff they used on Stars In Their Eyes when a bloke with a gammy eye and a limp would walk on stage in a wig proclaiming he was Tina Turner. Witches use it in their cauldrons to make themselves look more evil. Heston Blumenthal uses it to draw attention away from the fact that he's a pillock.
But more to the point dry ice, which is actually carbon dioxide at about -80C, isn't abrasive and would therefore be kinder to our walls because it simply 'lifts off' the contaminates in question. It also became apparent that it could well work on our terrible quarry-tiled floor in the Living Room and the painted sandstone windowsill in there!

I started to get excited so I made some phone calls.

A few days later the first quote came in and it made for sobering reading.
At thousands of pounds (more than one but less than five) to hire the stuff for a minimum of seven days, transport it to The Lodge, get trained and buy the dry ice it worked out much cheaper to actually pay a man to come over and do it for us in a fraction of the time.
So much for our 'do everything possible ourselves' ethos. And it meant I wouldn't get to play with new power tools <sad face>.

A week-or-so after that a very friendly chap in a van turned up towing a giant compressor to try test patches before we committed to the process. He set everything up and donned overalls, a full-face mask and ear defenders. In hindsight this is because he knew what was to come.
Me being me and despite advisories to the contrary, I was dressed in my many-pocketed Man Trousers and a T-shirt and was wearing a disposable mask, leaky goggles and ear plugs. Not exactly full PPE but as an enthusiastic DIYer I wanted to watch regardless of my own safety or comfort. This turned out to be something of a judgement error.

When Mr Dry Ice started blasting it soon became apparent that it wasn't doing the job Dawn and I had hoped for. Starting with the concrete-tough filth on the quarry tiles by the Living Room fireplace, he managed to shift some of the unpleasantness but it left behind gray stripes where the rubber underlay had been glued to the surface for decades. One or two tiles came up well, but overall it was disappointing. The thick lead paint on the bricks saw a similar result with some of the paint vanishing in an instant, but not all of it. The same went for the thick ingrained soot in the back of the firebox and the sandstone windowsill. Close, but no Cuban cigar.
Determined not to be outdone, he tried various chemical remedies here and there, none of which helped much. Blasting those same areas afterwards shifted a little more muck and paint but still the results were less than perfect and even if they had worked the price was staring to go up.

Undeterred, out came the trump card.
As I'm sure you already know, (Mg+2, Fe+2)2SiO4 is a natural mineral commonly known as olivine. With individual grains being around three times smaller than sand grains it's much less abrasive than sand and although still classed as an abrasive we were running out of options. It was now or never. It had to be done.

The Living Room in the middle of the day
There are four things in this picture:
A lightbulb, a man, a window and lots of dust
As soon as Mr Olivine started blasting I realised why he had raised an eyebrow about my attire. Whereas dry ice literally vanishes on impact, olivine doesn't. It creates dust - especially when it hits the soft lime mortar between bricks at 20,000 mph.
And when I say 'dust' I don't mean the thin layer of skin cells you wipe off your TV screen every six months so you can see afternoon repeats of Magnum PI better. I mean dust. Thick billowing clouds of eye-scratching, nose-clogging, skin-exfoliating, tooth enamel-removing, cat-burying dust that settles in layers over everything you own and also over surrounding towns and villages. The kind of dust that diverts aircraft.
It was only 10 minutes after he finished that I realised it was still daylight outside and could find the door.

But it worked!

Test patches on the chimney breast, floor and windowsill came up so well that I almost hugged Mr Olivine and told him I wanted him - and the last time I did that I got community service for a month.
The painted bricks were no longer painted but still looked like they belonged to an old house; the soft lime mortar between the bricks had taken a hit but was almost white again rather than a grubby grey; the quarry tiles were reddy/orange with white marbling beneath the glue and the sandstone windowsill was blemish-free. It was perfect.

So he rocked up last Wednesday to do the lot.

An oak beam and a vaulted ceiling
This is the kind of thing you find when you have a couple of hours to kill
Dawn had decided to work from home for the day and during a delay in proceedings (Mr O was having van trouble) we, on a whim, pulled down a suspended ceiling in the hallway by the front door and ripped off a load of lath and Artexed plaster next to it.
In doing so we discovered that above the suspended ceiling was a steep vaulted ceiling all the way up the sloped porch roof, with the limed house-side wall propped up by a beautifully-aged oak beam.
So, flying by the seat of our pants, we pulled off all of the lime down to the brick on that wall (it was badly cracked anyway) and prepared it for blasting. The whole process from "I wonder what's above this ceiling" to the whole thing being ready happened so fast that it left my head spinning. I like to plan things, you see, not act on impulse. But the prospect of Mr O's imminent arrival had us both giddy with excitement so within a couple of hours it was done.

Rather than bore you with more words I'm going to tell the next part of this tale in before/after pictures.
You should know that Mr Olivine didn't leave until gone midnight, and in the 12 hours he was here he barely stopped. Other than cups of tea his only downtime was for a pizza we forced him to eat in case he passed out.
I did take over for 10 minutes in the Living Room while he had a cuppa, but that was only so I could say that I managed to do a bit despite us having to get a pro in...

Although some work still needs to be done, especially on restoring the quarry tiles, the result is outstanding and has marked one of the biggest and most encouraging steps forward in the whole project.

One final thing - the clean-up took us four days and I'm still getting dust out of my nose. Andy and SamTheDog popped over for half an hour during the work and he said he could see the dust cloud before he could even see the house. That's how bad it was.

Having stayed in each room to watch the work with my inadequate goggles and mask, there was a moment in Bedroom 1 when I couldn't hear anything but the blaster and literally couldn't see my hand in front of my face while I was being bombarded by dozens of disoriented flies. It got so bad that I couldn't tell where I was in relation to anything else and I started getting vertigo... that was an interesting moment, it has to be said.
I had the last laugh though because they were all dead in the dust next morning <happy face>.

Anyway, the pics.

Living Room


Bedroom 1

Bedroom 3

Best/worst of the rest

Even the walls needed to be vacuumed


  1. That is a serious amount of work! Well worth the lovely hard working man and his Ovaltine (it's how I kept reading it). House is really taking shape! Ruth x

  2. Excellent result, very very good but honestly, who doesnt know (Mg+2, Fe+2)2SiO4 is a natural mineral commonly known as olivine?

  3. That's some transformation - you'll probably be shaking dust from your hair for the next month but at least your brickwork will be lovely!

  4. I can still hear the blaster when I close my eyes at night...
    Some friends of ours had some of their walls blasted by the same fella at the weekend and I helped them clear up on Monday. The mess was indescribable. It brought back memories that are still far too raw to think about.


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