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Sandblast, yes or no?
https://www.ausmini.com/forums/viewtopic.php?f=2&t=86203		 Page 1 of 1
Author:  bluewhitecoopers1968 [ Tue Jun 24, 2014 4:08 pm ]
Post subject:  Sandblast, yes or no?
What are people's thoughts on sandblasting old alloy wheels to remove paint? Also an engine block including the gearbox, also to remove old paint? The parts will be bare before hand of course.
Cheers.
Author:  Mick [ Tue Jun 24, 2014 4:12 pm ]
Post subject:  Re: Sandblast, yes or no?
Just my opinion, its difficult to remove the grit from engine galleries and hidey holes. You can get a great finish from hot tanking.

I did blast my gearbox case for the last resto, and spent an age removing it from the blind thread holes and crevises. There's always a lingering doubt too that you got it all.

Nothing wrong with wheels however, as long as its soft media for aluminium. They will look a million dollars.

Just my opinion.
Author:  peterb [ Tue Jun 24, 2014 8:21 pm ]
Post subject:  Re: Sandblast, yes or no?
Soda blast them, then pressure wash the powder out, comes up unreal.
Author:  Besser [ Wed Jun 25, 2014 11:38 am ]
Post subject:  Re: Sandblast, yes or no?
Have the engine hot tanked, it's standard at engine rebuilders after the breakdown as it removes oil, carbon and paint. If necessary paint stripper then wash again or just paint over it. If it survives the hot tank then it's probably not going anywhere.

Sand blast wheels only when looking to paint. For polished try a hot high pressure blaster then alloy friendly paint stripper then HP blast then polish.

My hot HP blaster has been the first step in all my builds and is does wonders.
Author:  Kennomini [ Wed Jun 25, 2014 5:50 pm ]
Post subject:  Re: Sandblast, yes or no?
I sandblasted my assembled engine to give it a freshen up paint job. I just removed the accessories and bolted blanking plates over and holes.
I have sandblasted mag wheels and after some wet and dry sandpaper and a polish they come up fine.
Author:  peterb [ Wed Jun 25, 2014 6:31 pm ]
Post subject:  Re: Sandblast, yes or no?
Use the glass beads you get from Repco, tradetools, etc. Works well, then quick W&D then polish. Don't use the corse pink garnet stuff, it's only good for bridge girders.
Author:  justfanginaround [ Wed Jun 25, 2014 6:56 pm ]
Post subject:  Re: Sandblast, yes or no?
re sand or blasting an engine block or gear box housing. miss a few grains and all rotating or sliding surfaces will be worn out before ypur engine warms up. yours ric scott
Author:  Mick [ Wed Jun 25, 2014 7:12 pm ]
Post subject:  Re: Sandblast, yes or no?
peterb wrote:
Use the glass beads you get from Repco, tradetools, etc. Works well, then quick W&D then polish. Don't use the corse pink garnet stuff, it's only good for bridge girders.


The Bengal garnet is great stuff in a medium grit, but yes, for steel parts only.
Author:  bluewhitecoopers1968 [ Wed Jun 25, 2014 8:37 pm ]
Post subject:  Re: Sandblast, yes or no?
justfanginaround wrote:
re sand or blasting an engine block or gear box housing. miss a few grains and all rotating or sliding surfaces will be worn out before ypur engine warms up. yours ric scott

Yeah I think hot tanking is better now. I went down to my local engine builder and was convinced that he can remove 99% of paint in the process and if in not happy he will leave it in overnight.
Author:  peterb [ Thu Jun 26, 2014 7:36 am ]
Post subject:  Re: Sandblast, yes or no?
If it's in bits, hot tanks the go. Any paint that doesn't come off after o/n dip, ain't coming off and you could be confident to paint over.
I did the glass bead wash on my motor. There was no repairs needed and I wanted to paint it and as KM mentioned, I sealed it up REAL good.
Author:  Westwazza [ Thu Jun 26, 2014 10:34 pm ]
Post subject:  Re: Sandblast, yes or no?
Regarding the alloy wheels, I have 5 quite original Contessa's that are sitting in my shed that I'd like to bring back to life. They are dull but look very straight and I don't mind a little hard work if it pays off….. What might be a plan of attack for this little project?
Author:  bluewhitecoopers1968 [ Fri Jun 27, 2014 7:31 am ]
Post subject:  Sandblast, yes or no?
Westwazza wrote:
Regarding the alloy wheels, I have 5 quite original Contessa's that are sitting in my shed that I'd like to bring back to life. They are dull but look very straight and I don't mind a little hard work if it pays off….. What might be a plan of attack for this little project?


I think most people are saying that sand blasting is the go. I'm about to drop off mine today. I'll post some before and after pics later :)
Edit: the bloke that's doing it only does automotive stuff and showed me some samples of his work on alloy. He uses a 2 step process. The first is with fine media and follows up with glass beads.
Before pictures....
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Author:  peterb [ Fri Jun 27, 2014 10:24 am ]
Post subject:  Re: Sandblast, yes or no?
There needs to be a bit of clarification regarding blasting. There's heaps of different types and some may get 'caught out' using the wrong ones.

'Sandblaster's' use anything from fine sand to rocks. The fine sand is for paint/light rust/corrosion and the heavy stuff for really rusty beams machinary etc. Make sure the guy's doing it are experienced or you might end up paying for something that could end up scrap metal.

For alloy etc soda is the ideal stuff, it's fine and doesn't pit the metal. The next best thing is fine sand but can make for extra work when polishing is desired. There's other types of media, plastic beads , nut shell, ice etc, but these are more of a specialists type. I've seen purfectly good cars reduced to junk by inexperienced abrasive blasters.

The best idea if you're not sure who or what to use is to ask around, it's better to spend time asking than to spend more time trying to fix someone elses stuff up.
Author:  drmini in aust [ Sat Jun 28, 2014 6:40 pm ]
Post subject:  Re: Sandblast, yes or no?
I did my s/h $20 ea Contessas with paint stripper, machined the gutter rash off, then wet sanded the shiny rims in the lathe with 400>600>1200 wet/dry paper.
Next I masked the shiny rim bit and etch primed the rest, and gave them about 6 or 7 coats of VHT's quickcoat acrylic gloss black.
They came up pretty nice.
No way I would sand blast Contessas.
[edit] or gearboxes. Grit problem as others said.
I found paint stripper works fine on the outside. But one S box I did recently had 45 years of Castrol black sludge stain inside. I got it soda blasted and it then looked brand new.

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