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Hello; I have doubts about what to do with the cases when I finish the dismantle.
Years ago, I sent 2 engines cases to mirror polish. Look great, not factory; however to preserve the shine you need to keep polishing in weekly basis. With the years passing; rain, humidity and plenty of road riding; the shine is not on but the cases look clean and correct.

Bead blasting on cases, do not factory and in no time you have an old look again. May be too aggressive for the bearing cavities and bushes etc?

Vapor blasting seems the way to go? I do not know a shop here doing that for motorcycle cases but I am searching.
Question regarding this method if the clean look is durable? or is like bead blasting?

Soda blasting the cases; I think that is not a good method; too aggressive may be for the bearing holes?

What about the "hydro blasting" seems similar to sand or bead blasting but with water?

Thanks

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There is still a medium used when vapour blasting.
With soda blasting I believe the soda is soluble.

I’ve had items vapour blasted and had to do a thorough clean up job of the internals afterwards. And that was with me blocking all the holes up as best as I could. Though blocking the holes stopped anything going inside, it did crowd around the taped areas.

The bits I have had soda blasting (soda is brilliant for removing paint from steel without causing other damage like sand blasting can) has given a great finish for primer and not needed and residue to be cleaned off after. (Though I do clean all my items before I fit them)

Bead blasting will change the finish of the surface. I had a 400/4 head and barrel bead blasted. The original finish on the fins was really smooth. It wasn’t when it came back. The next set I had done I did vapour blast’. These came out like new. 10+ years on they still look as good.


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I've used vapor blasting on engine cases and heads a few times, as Allan mentions above, they come out like new and the finish is durable since the process closes the alloy pores and stops dirt entering. Bead blasting opens up the pores and attracts dirt, so I wouldn't try that.

I believe hydro blasting is the same as vapor blasting, essentially its a mix of hot water, cleaning chemicals & media.

I've found that the finish with vapor blasting does eventually fade after 10 years or so, probably due to oxidization etc.

One option might be to paint the cases with high temp silver engine enamel which is what many Jap bikes use and is highly dirt resistant.

Last edited by gunner; 09/05/21 10:01 am.

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Tried them all and now use ultrasonic cleaning, some citric acid and/or oxalic acid accelerates the action and brightens the finish.

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Soda blasting is about the least harmful medium. It goes on dry, but is water soluble. Apparently used on aircraft to avoid metal damage.
Dry ice is also used. Same stuff used for mists in theatre. Tiny pellets chip off the dirt/paint and sort of melt/vapourise.
Both might need a rinse under a tap but not much more

"Vapor" or "aqua" blasting is some kind of media (shot/glass etc) along with high pressure liquid that requires thorough cleaning.

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My personal preference is soda blasting.
It is not too aggressive— in fact for some people it is not aggressive enough.
However I prefer to spend more time and get to a good clean finish gradually.
The residue is soluble in water so I give the parts a good rinse in hot water.
The process is quite messy so I do the blasting in the road outside the house and then hose the road down.
No one complains as I am known locally as the Eccentric Englishman with the old bikes.
What I particularly like is that there are no residues of walnut shells, sand, or other blasting media.
Just my two cents worth of course.

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...thinking in what you guys are saying about the Soda; the other day I used it to remove the paint on a windows wood frame. I dissolved it in water and applied over with a brush.
Do not know how do you guys did in your home workshop because I think an special gun is needed; like the ones the dedicated shops have; so I am thinking; but may be is useless, to do the same type of method described. May be 3 or 4 times?

-Do not forget that I am talking about the cases finishes not about to clean the interior part.

I see these cases and look normal; no oil etc but also look "used" not "like new"; is the soda blasting a good way to see them after and would look "like new"
I do not know exactly how server can I use (now) to upload photos of these other cases that I had mirror polished; to have an idea or may be one of you have a photo after the soda blasting and then after a few years of use. That would be great to compare.

Thanks

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Go to face ache and have a look
You can buy special kit but I jaut made one from a longish air duster and a drink bottle
The bottle I am using now originally had iced coffee in it so it has a wide opening which makes for easier loading.
Made it about 3 years ago and just replaced the duster this week as the soda has finally made a hole in the outlet
The duster I use has a 30 deg bend at the outlet end and worked a lot better than the original which was strait as most of the time I can keep the bottle vertical .
Gone through around 10kg of animal feed grade soda which was bought to "try out" ( because it was cheaper than human soda and a lot cheaper than blasting grade soda , so far it works quite well.
Blasting soda is the same chemically just bigger crystal size so should be more aggressive & less prove to caking .
One of those simple tools that after a while you wonder how you got by without.

The finish is good & very clean but has to be washed off with hot water before painting.
It is not passivating so moisture on the cleaned surface will cause corrosion.
The water used in vapour / hydro blasting contains passivators to prevent corrosion.
However the best is either paint or wax long term
Aircraft clear is particularly good on alloy .


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The soda used with hot water is caustic soda and would dissolve aluminium.
It also removes skin

Soda blasting uses bicarbonate of soda (baking powder) but in various grits

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Hi; yes; I saw that some use the word "Soda" for sodium bicarbonate.
Thanks


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