Soda blasting.

[Alistair D]

Very interesting that something as soft as bicarb would make such an effective cleaner.

I wonder how effective it would be for cleaning valve pins and valvebase contacts on B7G, B8A and B9A connections? It may also be of use for silver plated switch contacts that suffer tarnishing problems.

Do a Youtube search on soda blasting. There are a few videos of cheap DIY blasters. These may not be ideal but would be a good way to try it out before spending too much money on something you may never use again.

Al

[Retired]

Hi,

If you only want to clean the odd item then as you say Robin use the method which suits you best without going to a lot of expense.

Thanks Al, yes it is strange that such a soft medium as soda strips paint and dirt so easily; I wonder who was the first to ever try this? Soda isn't abrasive like hard mediums so doesn't remove paint or dirt by abrasion; each grain of soda is fired from the gun at such a high velocity that it explodes on impact and it is these many tiny explosions releasing force which does the job.

Soda blasting would be ideal Al for cleaning valve pins but care would be needed not to remove the valve markings from glass; soda won't damage glass. Anyone owning a small compressor could as you suggest Al try soda blasting very cheaply indeed; the videos on YouTube you mention show just how easy and cheap it is to get started; it all depends on what you want to blast and how much money you want to spend; I still haven't used my new soda blaster because of the poor weather; I've no intention of trying to blast inside a closed garage unless I firstly make a blasting cabinet which is something worth considering given our climate?

Kind regards, Col.

[Bazz4CQJ]

Although soda blasting has never really taken off in the UK, I recall reading articles about it on the web by US/Canadian/Aussie DIYers some years ago. There are numerous items on the web and some of the kit used is commercially manufactured, some is elegant homebrew and some is extraordinarily cheap and cheerful homebrew.

If you look up the data on hardness of materials, the stuff is surprisingly hard, though I would imagine that actual performance depends on the nature of the particles obtained, but some guys were using "supermarket grade" quite successfully. My interest probably relates more to automotive tasks rather than radio, where the use may be quite limited.

As for DIY at pressure, I think I'm OK there as I spent some years working professionally with CO2 at 900psi and 800'C and then water at 2300psi at 325'C. Of course, that was in those far off days when the Brits built their own nuclear power stations...and GaAs FET's....and rocket engines....

[Retired]

Hi,

Only recently have I heard of soda blasting but as you rightly say Bazz in the states it's been around quite a while and it's possible to have a guy with an industrial soda blaster visit if the job is big enough.

I've found it very interesting watching the YouTube videos on all aspects of soda blasting showing the very basic $15 home made blaster right up to the big blasters which will soda blast paint from cars to planes with little effort.

I'm still keen to try my blaster out but it remains wet outside and I don't know what clean up would be like on a wet drive; it's also cold so all is normal.

When I worked at Brook Motors we tested the explosion proof motors using water pressure.

Kind regards, Col.

[Retired]

Hi,

At last the weather finally let me play with my new compressor and soda/hard medium blaster this afternoon.

Setting up wasn't straightforward because I had to play around with air connectors in order to connect the new compressor; air/water separator and blaster. Eventually I had the air/water separator mounted neatly on the wall near the compressor and after charging the blaster with half a bag of hard medium switched on. As air pressure came up I could hear air escaping and traced this to a massive air leak on top of the new air/water separator? I was already holding my breath that it wouldn't pour with rain so rather than waste time trying to sort the problem simply disconnected the unit pressuring the blaster directly from the compressor but I must add these blasters are supplied with an on-board air/water separator but it is recommended to add a second unit just to ensure dry air goes into the blaster.

The set up looked most impressive and my first impressions were most favourable as I started to blast paint from the Wilmac bandsaw. At first I was a bit too keen holding the blasting nozzle too near the work but I soon found out that if I pulled back about four inches the spray pattern was much more efficient. It was wonderful to point the nozzle and watch the paint being stripped slowly but easily; I found after I settled down this blasting to be therapeutic. For my safety I had donned dust mask; safety goggles; ear defenders and rigger gloves. I tried using the hood supplied but it proved a nuisance misting up my glasses so was discarded. I was happily blasting away until the blaster stopped removing paint although plenty of air was still being discharged? There is a blow off valve to the base of the blaster tank to clear the regulator unit so I gently opened this to see a jet of hard medium be discharged then quickly closed the valve; from then on the blaster would work for a while then stop paint stripping but I found mostly I could simply tap the regulator unit very gently with a spanner then resume blasting. With daylight rapidly failing I had to call it a day but I was very pleased by my very first effort in using this blaster; the bandsaw side and some edges took about half an hour to strip paint from so it's not a rapid process unless of course a much bigger compressor is available allowing a bigger nozzle to be used; I was using the smallest nozzle and although it was cold and very blustery enjoyed this new experience. Then it started to rain so I quickly swept and tidied up. The compressor and blaster were put away but I left the hard blasting medium still in the blaster; I don't know how much blasting medium was used but the blaster felt quite heavy as I wheeled it into the garage; this is my punishment for trying to work outside in Yorkshire; it seldom changes all year round and I'm usually working in a black hole but what a result?

Hopefully tomorrow I can play with the blaster a bit more and I want to inspect the second air/water separator to see where it is leaking air from? I'm pleased I decided to sell my 2hp compressor and buy the new 3hp compressor because all during blasting the compressor was running; the air supply to the nozzle was sufficient to do decent blasting so I would say a 3hp twin cylinder compressor must be the minimum unless prepared to wait ages for a smaller compressor to build up pressure which shouldn't be a problem if only blasting small items like a radio chassis. If using the blow off valve to clear the regulator I would suggest blowing off into a clean container such as a bucket then the medium can be used rather than wasted.

I'm colour blind and unaided by poor light I had trouble blasting the primer coat away because it looked the same colour as the cast iron but a quick inspection revealed a decent job.

Personal safety is a must whilst using one of these blasters; after blasting this afternoon with my safety kit worn I didn't suffer any adverse effects at all other than getting dusty; my nose and eyes remained clean even though occasionally felt a bit of stinging to exposed skin; I quickly learnt how to blast whilst avoiding blow back.

I was told the hard medium would be more suitable for blasting the bandsaw and this proved good advice; the blasted surface is nicely etched and once dusted will be perfect to receive the new paint. It's been highly frustrating owning this kit for a couple of weeks whilst the weather did its worst but having said this I feel there is yet even worse weather to follow for at least the next two months. I don't recommend blasting in a home workshop or garage unless a proper blasting cabinet is made because the dust gets everywhere and this hard medium will not be kind to machinery or bearings. I'm eager to have another go with this blaster.

I'm moaning about the weather but many are much worse off than me being flooded out of their homes. Last year I installed flood defences to our bungalow so now it remains dry under the floors but recent storms brought down a huge conifer taking me nine days hard graft to clear.

Kind regards, Col.

[Sean Williams]

Colin, nice setup, I would upgrade the coiled air hose to a decent length of 3/8 rubber - it will heat up less, and as a result reduce the possibility of condensate build up.

I would also advocate good thick gloves, and arm protection - the blasting hood is uncomfortable, but to be honest the safest thing to blast under.

I spent a short time blasting commercial vehicles, using a much bigger setup, so have some experience of this.

Good DIY results though!

[Retired]

Hi,

Many thanks Sean for your useful suggestions.

Because of the faulty second air/water separator I didn't actually use the coiled plastic hose instead using the standard reinforced hose similar to a garden hose. I dislike the coiled type hoses with a passion but I tried using it as it coupled to the second air/water separator with its connections.

My safety kit worked well; I was wrapped up against the cold weather so my arms were protected; the only exposed skin was to my face around the dust mask and goggles and it was here I felt the occasional tingle from blow back. I tried using the hood which was cumbersome in the extreme but I found after a short while I went blind as my glasses fogged up so had to resort to dust mask and goggles. I was also wearing a woolly hat and ear defenders. I would never use one of these blasters wearing just the hood because in my limited experience a good dust mask is essential after all I can't replace my lungs.

I was pleased with the performance of this set up accepting it's limitations but you must have really enjoyed blasting with heavy duty kit Sean; I feel I'm in for a love hate relationship with my blaster; it does a good job but it's such a downright pain trying to blast in our climate and the clean up afterwards has to be seen to be believed; our drive resembled a dirty beach even after only 30 minutes blasting.

I got up early this morning hoping to continue blasting but its another wet black hole outside still half an hours blasting in two weeks isn't bad going to say I live in Yorkshire; perhaps it will dry up a bit later today?

With hindsight I should have taken the bandsaw items and had them blasted by one of our local blasting companies saving lots of money; time and hassle but then I'm an idiot who refuses to be beaten by our dire climate. I could also have chemical stripped the bandsaw ages ago and by now had it fully rebuilt but where's the hardship and challenge in that?

Kind regards, Col.

[Retired]

Hi,

I've now had time to do more blasting so can update on the blasters performance.

I've never used a soda/hard medium blaster before and my blaster was brand new as was my 3hp compressor. I was advised to use the hard blasting medium which I bought two bags of (50kg).

Both success and failure; the positive side is that using the blaster has left the two main bandsaw components perfectly clean and ready for re-finishing once dusted off so in this respect it proved a success and did what it was designed to do.

The negative side however far outweighs the positive side on a number of counts. Firstly there is the cost of the equipment which in my case amounted to around £400 which I add I was happy to pay this being for the compressor; soda blaster; second air/water separator and 50kg of hard blasting medium. In use the second air/water separator failed immediately not even coming up to pressure due to a massive air leak so this was disconnected and still remains unused. Lots of safety kit needs to be worn; ear defenders because the compressor is very noisy; eye protection goggles; dust mask and gloves. Yesterday I spent most of the day blasting on our driveway; I had donned a tee shirt; shirt; jumper; body warmer and top coat plus the trousers etc; even so well wrapped up I could only stand an hours blasting before feeling too cold to carry on; just kneeling or crouching on the drive didn't generate exercise to keep me warm so I was at the mercy of the icy breeze coming up the valley.

I did however spend the afternoon in more comfort; the sun was shining raising the temperature a couple of degrees so I settled down to a session. The on-board air/water separator proved virtually useless and as a consequence the nozzle kept emitting a jet of water spray which in turn had blocked the valves; I was constantly either operating the blow off valve to clear the blockages or tapping the valves with a spanner which I found most infuriating. The compressor was running constantly under load giving around 2 Bar at the blaster during blasting. Blasting under these circumstances was incredibly slow; when the blaster worked as it should it was acceptable but the water ingress was slowing the whole job down.

Blasting by it's nature is a very dusty operation and this was borne out by the driveway resembling a dirty beach after even only a short blasting session. The debris from blasting clings to a wet driveway and surrounding area. If soda blasting and the soda gets onto vegetation it needs washing off otherwise the soda turns the vegetation brown. I used a wooden stick as a dipstick to determine blasting medium level in the tank but only after releasing air pressure. The heavy hose and nozzles are prone to wear so are consumables.

The bandsaw isn't big but the two main components must have taken over five hours to fully blast using at least 1 bag of hard blasting medium (£17 bag). Whilst blasting the aluminum component I could smell the aluminium which was being removed; this wasn't a problem but for a job requiring aluminium to remain shiny then soda must be used.

Without doubt the water problem proved the biggest obstacle but given how bad our weather is I don't have time to play around or investing in air/water separation expecting this blaster to be virtually plug and play without incurring lots of additional expense.

I don't regret in the least buying this blaster (a Christmas present in fact from my lovely Bron). I've always fancied owning a blaster and now that I've got one and gained some experience in using it do I keep it and sort out the water problem or sell it on? I could of course construct a blasting cabinet in kit form allowing the cabinet to be stored when unused; this would cut down on the dust problem. The water problem could also be resolved but at a cost yet unknown?

I like to experiment and having seen YouTube videos of home made soda blasters costing $15 I wonder if I could take this a step further. I'm thinking on the lines of using my very cheap air blow gun which is trigger operated for delivering air but add an additional nozzle after the air nozzle this nozzle being ceramic; between the two introduce a gravity feed hose for the blasting medium. If this would work then it would eliminate the need for the pressurized tank together with its many valves and also the problem of water ingress? A simple valve and reducing jet could be added to the gravity feed and the whole set up would cost very little indeed; as I say it's just a thought at the moment and I'm thinking aloud.

I'm unable to carry on blasting because its white over with a deep frost this morning so I think I'll postpone this bandsaw restoration for a short while and investigate the air/water separator problem which I can do in the closed and heated garage.

So far the negatives far outweigh the positives for me in blasting but for anyone with premises large enough to blast in perhaps the water ingress won't be such a big issue; I'm not in any way complaining just trying to give an honest account of my first blasting venture and I certainly don't wish to deter anyone from giving blasting a go because in spite of the cold conditions and the blaster problems it was most satisfying watching paint be removed down to bare metal with so little effort.

Kind regards, Col.

[threeseven]

From my experience the problems you've had were predictable. Virtually everyone I've known to try DIY blasting has under estimated the CFM of air required. So when a small hobby compressor is used it inevitably either can't maintain the pressure required or runs constantly to do so. This causes the air leaving the compressor pump to be very hot so when it hit's the cold receiver it just creates massive condensation, even worse in cold conditions.
The only way to prevent that is to install a powered dryer/cooler between the pump outlet and receiver inlet. That is expensive.
Then there is the problem of running a hobby compressor continuously when they aren't designed for a continuous duty cycle. They don't last very long with that use, particularly the direct drive units which run at higher speed.
So, really a large compressor or multiple smaller units are required but then there is the problem of an adequately large power feed. The largest single phase compressors generally available are 5hp, but even these aren't really adequate.
I was once asked to supply a compressor to operate a small blast cabinet at a friends restoration workshop but he was on a budget. I told him that he needed at least 100 CFM, preferably 200 and that the cost of the electricity just to run it would be massive, 100 CFM would equate to about 22KW! He told me I was being excessively pessimistic and gave me a budget that would only buy a used 50 cfm unit that needed much recommissioning to be useable.
So I did this, the compressor worked as it should but he was soon on my case as it wouldn't maintain pressure and was costing a fortune to run! My reply was obvious!
Blast cleaning is probably the most demanding compressed air application their is and I know of a number of professional companies that now use diesel powered road drill compressors as they have the capacity and are designed for continuous use.

[Sean Williams]

Pot type blasters are quite inefficient, but are ideal for larger stuff.

I fully intend to purchase a tabletop blasting cabinet, the air requirements are much lower, and as a result of the size constraints, the size of item to be blasted is smaller. These run quite well on smaller air supplies.

I have a 5hp compressor, and a couple of larger tanks laying around, so, as and when I make a start on this I will create as much reserve air as possible, I will also use a much higher diameter air supply line than specified, this will tend to remove the localised hot spots.

Certainly wouldn't want to be blasting in the open air, the mess is terrible!

[threeseven]

The size of the receiver doesn't change the capacity of the compressor, more receiver capacity just delays when the pump kicks in but it still has to fill that bigger receiver so nothing is really gained.
Larger diameter supply pipe work does reduce pressure drop from delivery to take off. Using a filter at the point of take off and keeping the connection hose from there to the consuming unit also reduces moisture in the air.

[Sean Williams]

I appreciate the receiver will not alter the capacity, but it will reduce the temperature differential of the air supplied, and give a larger area for the moisture to condense - I prefer to have the moisture in the tanks, instead of in the lines.

[Radio Wrangler]

The bigger receiver gives you a longer run between longer breaks while you wait for the pressure to recover, and this can be less frantic although the job overall is no quicker.

David

[Retired]

Hi,

Many thanks threeseven for your interesting information. In my case I didn't underestimate the CFM or compressor size because I sold my 2hp compressor and bought the brand new 3hp compressor recommended by the blaster supplier for powering this particular blaster.

For DIY use in a home environment having the compressor running flat out occasionally for a few hours shouldn't damage the compressor as long as it is fully lubricated. My previous 2hp compressor served me well never missing a beat in over twelve years.

Thanks Sean; I'd try using your 5hp compressor as I'm sure it will be on top of the job using one of these blasters with the small nozzle fitted; my 3hp blaster puts enough pressure out but with continuous running. It all depends what you want to blast and how often. I don't have any choice when it comes to blasting; either outside or not at all because I've no intention of trying to blast in my garage other than if I make a dedicated blasting cabinet to contain the enormous cloud which blasting creates.

I think the simplest way to judge one of these blaster/compressor set ups is very simple; if the blaster is using more air than supplied by the compressor then no number of additional tanks or cylinders will help.

Without doubt the biggest problem I encountered was the air/water separation; when I next go into the garage I'll have a close look at the failed second air/water separator; having already owned this new kit for a couple of weeks I was keen to try it out but could only do so dodging our dire weather. I intended to go into the garage tomorrow but tonight our tumble drier dictates otherwise as its packed in so yet another silly diversion; I just hope I live long enough to finally settle down to a full day pottering around in the garage; being retired is a full time job?

Kind regards, Col.

[Retired]

Hi,

This morning I washed a pile of dirt on our driveway finding a car under it. It was a beautiful sunny morning and for a change I could see what I was doing. Next job was to investigate the second air/water separator problem. When I set everything up I was in a panic to get blasting as quickly as possible due to a window of opportunity in our dire weather. I had attached this separator to the garage wall making coupling easy but in a rather inaccessible position.

I removed the separator from the wall and holding it my hand connected it to the compressor switching the compressor on; what; absolutely no air leak? When I tried to use it in anger it was leaking masses of air then I spotted my blunder; I had only connected it wrong way around first time in the doom and gloom so it was a very quick fix but a bit late after suffering the way I have for hours on end using only the factory installed on-board air/water separator.

I don't mind doing stupid things and letting the world know about them because hopefully others will learn from my mistakes; if there are two ways to do a job I'll always do the job two ways?

My mistake though has proved the factory installed separator is woefully inadequate for the job; perhaps now I've got my act together the second separator might help a bit?

Oh for some decent weather then I won't have to fly around like an idiot all the time?

Kind Regards, Col.