question Cleaning old metal

[Aussie]

Having bought an old Saracen/Ferret turret, I'd be grateful for advice on the best way to clean it up for painting. Would sand blasting get it back to good metal, or would needle scaling be better? Or would most recommend just getting to work with a wire brush (though that sounds awfully tedious)?

After getting it back to clean metal, what's recommended for rust-proofing and priming?

Thanks

James

[paulbrook]

For serious scale use a needle gun, then blast clean.

 

Blasting is great - I just had a whole Antar done - see the last few pictures in this sequence

 

http://www.robinsonblastclean.co.uk/epages/es144606.sf/en_GB/?ObjectPath=/Shops/es144606/Categories/Before__after_photos/Metal_photos

 

These days the medium of choice is recycled glass. Nothing comes close for speed and cost effectiveness and the surface finish is perfect for a good quality zinc rich primer.

 

I am going to introduce a dip system soon (I am testing a system to do the inside of fuel tanks at the moment which as you can imagine you dont want to sandblast), using a suitable mix of chemicals, and some swear by electrolysis. Those might be a bit of a struggle for your turret though, but it will be good for freeing off rusted mechanisms and cleaning smaller items.

 

If you need any advice then get in touch!

[Ian L]

For serious scale use a needle gun, then blast clean.

 

Blasting is great - I just had a whole Antar done - see the last few pictures in this sequence

 

http://www.robinsonblastclean.co.uk/epages/es144606.sf/en_GB/?ObjectPath=/Shops/es144606/Categories/Before__after_photos/Metal_photos

 

These days the medium of choice is recycled glass. Nothing comes close for speed and cost effectiveness and the surface finish is perfect for a good quality zinc rich primer.

 

I am going to introduce a dip system soon (I am testing a system to do the inside of fuel tanks at the moment which as you can imagine you dont want to sandblast), using a suitable mix of chemicals, and some swear by electrolysis. Those might be a bit of a struggle for your turret though, but it will be good for freeing off rusted mechanisms and cleaning smaller items.

 

If you need any advice then get in touch!

 

Hi Paul I notice they are based in Appleby, Cumbria, operating throughout the Northwest & Scottish Borders

do you know of a company in Southern England that uses the same process ?

[paulbrook]

Sorry I don't - but someone will I am sure!

[andym]

Sorry I don't - but someone will I am sure!

 

I'm about to get K Blasting (http://www.kblasting.co.uk) to blast and paint my Abbot and 432. The owner has MVs himself so knows what he's talking about!

 

Andy

[Ian L]

I'm about to get K Blasting (www.kblasting.co.uk) to blast and paint my Abbot and 432. The owner has MVs himself so knows what he's talking about!

 

Andy

 

Ummmmmmmmmmm Devon / Cornwall still 200+ miles away

[andym]

Yes sorry - just noticed the "Oxfordshire" bit!

 

Andy

[paulbrook]

Yell.com lists quite a few blast cleaners in Oxon - worth ringing round and having a chat.

[Aussie]

Thanks guys.

 

I noticed Fertan mentioned elsewhere in the forum - somewhere in the tank area.

 

Do you treat with that before priming, or isn't it necessary?

James

[Ford Laat]

I Had this Ford F60 chassis done by a mate who does this for a living in the Swindon area !

[utt61]

Blast cleaning is quick and very effective, the only reservation is that if your vehicle is not fully stripped the blast medium will get everywhere, so bearing etc are at risk. Also any bearing surfaces, joint faces, etc need protecting. Personally I prefer wet blasting to dry blasting, but there are fewer contractors who can do this work.

 

Needle-scaling is good for removing loose paint and scale but is surprisingly demanding and very slow, but leaves a good surface. RSI and vibration whitefinger is a real risk. Decent-sized industrial needleguns are expensinve and not easy to find (and if anyone knows a source, please let me know)!

 

Alternatives like HD wire cup brushes in angle grinders are good for removing paint and rust but don't leave a very good surface - it tends to burnish and be too smooth for good adhesion.

 

Generally when painting blasted or bare steel surfaces I use an acid wash, followed by the primer coat(s), undercoat(s), and top coat(s). This is effectively the same as using Fertan or similar, and will result in a good finish with excellent rust protection and very good paint adhesion.

[Aussie]

This might seem silly, however a bloke in Oz who has done up several armoured vehicles warned me today to not blast but to use paint stripper. Said that blasting damages the surface and promotes rusting.

It seems to me that I just need to treat the bare metal immediately - before it rusts - and I doubt that I'd have the patience to fiddle around with paint stripper and scrapers. The responses above indicate no problem with blasting (apart from need to protect bearings, etc) but does anyone think that blasting is a bad idea? Thanks for all your advice, by the way.

James

[Pete Ashby]

It's very much a case of horses for courses, Over the years I have used chemical paint stripper with wire brushes, sand blasting, iron slag blasting, copper slag blasting, bead blasting, chemical dipping and electrolysis all have merits and draw backs.

 

If you have heavy corrosion then sand or slag blasting will produce good results quickly, however remember that the very action of producing that nice dull grey surface removes significant amounts of surface steel. When steel is forged or in the case of sheet rolled the action and heat of production tend to produce at the surface of the metal a grain structure that is aligned and flat at the surface (that's why stock steel sheet is smooth to the touch) when you blast clean the surface you cut through the surface grain structure and expose the under layers if the surface is not then sealed with a high build primer and a undercoat with a high varnish content (ie gloss paint) you will get after time tiny brown rings that appear in the paint surface and will look like a case of measles after several years. This is the result of water moving down the open grain boundary of the steel and causing corrosion between the grains, known as grain boundary corrosion to metallurgist.

 

I now tend to use chemical stripping and wire brushes on good steel with an etch primer and gloss undercoat. I keep the blasting option as a last resort for badly rusted parts.

 

Pete

Edited July 14, 2012 by Pete Ashby