Soda blasting on alloys?

[richrich123]

Hiya,

A quick question if anyone could help or has tried this. One of my lines of work is alloy wheel refurbishment. This is via a mobile server (no workshop) so done in a fitted out long wheelbase van. The van has a single booth with extraction fan in the bottom that is used just for sanding and prepping the wheel (the dirty work) and another double booth that is clean and for priming and painting the wheel.

Sanding is all that is needed for most wheels to remove damage from the rim and key ready to prime but now and again I get some that have corrosion or corrosion bubbles just starting. I currently have to sand this away, back to bare alloy. This can take a lot of time but more relevant is that some alloy designs with lots of spokes or intricate design can be very hard if not impossible to get into by power sander and eve by hand can be hard and sometimes impossible.

I don’t have the space in the van to keep a big blasting pot and cant blast sand for example all over a customer’s back garden as it would leave a huge mess.

That was when I saw you can get a 25KG pot of Soda for about £25 and insert a probe with a gun and be able to blast.

Soda gun on ebay

From what I understand, it is less harsh than sand so would leave the alloy with a good finish ready to paint and I was thinking should be ok to blast the wheel in the prep booth in the van as the extractor in the bottom sucks out dust and dirt and deposits it into a bucket underneath. From what I can see, it looks like it could be a solution for the occasional alloy wheel with some corrosion to get it stripped quicker and easier than by hand sanding.

With an alloy wheel, it needs to be finished to at least 240 grit to get a good paint finish so blasting with rough sand/beads etc isn’t much of an option as I guess it would need several rounds of different grits to end up with a finish that is good enough to prime and paint on.

Has anyone with knowledge of blasting think this would be a suitable solution for the occasional alloy with some corrosion? If not, any other suggestions (considering it is a mobile service and I don’t have spare room for lots more kit)

I also know this question has variable such as the size of the wheel, how bad damage is etc but very approximately speaking, can anyone make any guestimate on how much soda would be needed to do the face on a single wheel. Would a 25k bad do a set of 4?

Any help or advice much appreciated. Compressor is 90 litre, 14cfm

Cheers

Rich

 

[rtbcomp]

That gun would be OK for shifting loose stuff, but I doubt whether it would shift corrosion, and certainly not primer.

I've never used soda, but I have used very worn out glass grit to get a good finish on alluminium, but from a pressure pot, not a syphon blaster. Again even with a pot blaster it's so easy to gouge the ally because the metal is softer than the paint. For that reason I avoid blasting ally wheels unless I can give them a good soak in paint stripper first.

 

[500e]

We are using soda on alloy but it is still messy, although you can in theory wash it away with water, there are numerous grades of soda, it is hygroscopic !! ArmexXL will help with this.
We have tried numerous makes of soda & all are affected by damp not just in the blast air but in atmosphere, it has to be dry to flow, The XL is the most resilient so far, a 25Kilo bag wiill make a mess.
We tried a large cabinet 2.5 x 1.5 x1.5 with a cyclone extractor still dusty,we were feeding through ling lengths, did the job great though.
We have ended up in the open on stands with water injection at nozzle.
Still have trouble metering the abrasive tried taps (cheap) Cresco valve (dearer) a Archimedes screw thing (we made) now onto a rotating sieve thingy we are making this will hopefully not require a pressure pot.
when things are going OK it is great But.

 

[richrich123]

Hi, thanks both for your replies. 500e, not sure what you meant when you said "we were feeding through ling lengths"? So you now do it outside, what does the water injection at the nozzle do? Sorry, I am 100% new to any kind of blasting. I presume whan you also mention metering you are refering to controlling how much material is used?

Are you using a syphon rather than from a pot? rtbcomp mention he is not sure if soda would be able to remove the corrosion. Everything I have read says it is great for alloy wheels as it strips but doesnt damage the soft metal. Its going to cost about £100 to buy a syphone and 25KG of ArmexXL which if it turns out to just be useless is a real waste of time and money hence I was hoping to find out if anyone has had any success with alloys and soda (or anything else that may work)

Cheers for your imput, much appreciated.

 

[gulf]

Soda is ok in a big blast pot like i have (it has a 3/4inch hose and 8mm nozel) - soda is good on paint or for cleaning uncoated alloy,not rust or heavy corosion,,but for a suction feed on corroded rims,its going to be a waste of your time.Id use glass grit if i were you and you'll have a keyd surface ready for primer on alloy rims much faster.Glass grit is available in various grades and cheaper than soda

 

[norlander]

Thanks for posting the question as you just reminded me about soda blasting.Some points to throw in for consideration-
think small scale (no pun intended) soda blasting is usually for small delicate stuff like cleaning up carburettors etc which can be thoroughly rinsed with water.
Like all blasting its messy and gets everywhere-not as bad as sand though-but you might have to knock up some kind of portable booth to contain the dust if your van booth was not up to the job??
Its probably not practical on a mobile basis?.
I think (personal opinion) blasting is really best left to pros with proper gear as they have differing mediums -sand/plastic beads etc availabe plus the kit with the oomph to blast the medium and recover it and the safety gear.
There is another option but I have no experience of it-and that is sandblasting with water using a karcher pressure washer, I assume the water will contain the grit and dust and be far less messy but I do not know as I have never seen it done, nor do I know if it would be too agressive for alloy wheels. I say Karcher as thats the only pressure washer make I can recall who have the kit-maybe others do it as well.
I was once pressure washing some steel wheels that had hammerite paint, I had connected the washer hose to the hot tap by mistake and it blew the paint away-no idea if it will work consistently or indeed on other stuff but maybe worth an experiment.
Also whats your compressor? mines 3hp and syphon guns are not much cop, pot blaster is not too bad on recyled grit.
Top of the range Dremel? more effective than you would think- might get into the nooks n crannies? mini die grinder from the compressor?
I modified some mops to a 6mm shank to get into tight spots, covered the shanks with self amalgamating tape to avoid scratches if the shank touched.
Brazed them on with OxyA, obviously need to be spot on with alignment or you get a wobblemop (which I would call a random orbital mop as I don't make mistakes and get all jobs right first time so I meant to do it).
Hope some of that is of use-good luck-let us know how you get on.

 

[rtbcomp]

One warning about glass grit. Particles can get embedded in the soft ally, so give the wheels a quick once over with fine abrasive paper before painting them

 

[rich the mechanic]

There is another option but I have no experience of it-and that is sandblasting with water using a karcher pressure washer, I assume the water will contain the grit and dust and be far less messy but I do not know as I have never seen it done, nor do I know if it would be too agressive for alloy wheels. I say Karcher as thats the only pressure washer make I can recall who have the kit-maybe others do it as well.

The pressure washer system is effectively a vapor / aqua blaster without the added air pressure and recycle part, cutting is all dependant on grit, I use a Guyson dry gravity blaster and mix 50/50 bol23 glass bead with crushed glass to get a good cut and finish however if it is just a finish then use just the bol23 or the finer bol24 then paint straight off after an air dust on alloy or steel, if I use the aqua blaster then we use plain crushed for cut as the water softens the impact to get that nice vapor finish it would need the bead but if used then the item needs to dry before it can be painted and alloy castings do have a slight porosity.

 

[mike k]

Soda will leave a mess too and I don't think it will provide a decent key for paint. All the mobile vans I've seen are "pop the bead and mask" operations so blasting wouldn't be an option and the soda would need washing off unlike other media's. Are you actually removing the tyre?
Mike

 

[norlander]

The pressure washer system is effectively a vapor / aqua blaster without the added air pressure and recycle part, cutting is all dependant on grit, I use a Guyson dry gravity blaster and mix 50/50 bol23 glass bead with crushed glass to get a good cut and finish however if it is just a finish then use just the bol23 or the finer bol24 then paint straight off after an air dust on alloy or steel, if I use the aqua blaster then we use plain crushed for cut as the water softens the impact to get that nice vapor finish it would need the bead but if used then the item needs to dry before it can be painted and alloy castings do have a slight porosity.

good points on selecting the right blasting medium for the job and as mentioned -the requirement for alloy to be thoroughly dried before painting-a point I would have probably learned the hardway.