The last time I rebuilt my M20, as I do with all restorations, I stripped it back to bare metal before respraying....

The tinware on the bike is largely what it left the Army with and was solid if not perfect...About 5-6 years ago I decided it was time for a rebuild again but kept putting it off in favour of other projects and so I could use it for Normandy again...Each year I just sprayed over bits, kept everything working and 'faked it' for another season...

Finally though the bike was stripped down for a well deserved overhaul which would consist mainly of a cosmetic refurbishment and a thorough check of the mechanical parts (the bike was on the road and running fine until then)....

However, when the sheet metal parts were stripped back to bare metal again the increase in the amount of corrosion that had occurred was remarkable, to the extent that on the rear mudguard particularly repairs to the wired edges and the removal of the riveted in 'bridge' pieces was required to put everything right...

Fortunately things hadn't gone too far and all repairs are now completed...

The bike has had plenty of use in all weathers since its last rebuild and reached the point about 5 years ago when the painted surfaces began to 'fail'...

This experience confirms in my mind what I have always suspected ...If you ride a 'barn find' or a bike that has just had too much use without restoring it to protect the sheet metalwork, and you use it a lot, you are likely to seriously damage it over a relatively short period...

How many people, for example, put oil onto the inside of the mudguards on their 'original' barn find that has lost a proportion of its paintwork?....Ian

email (option): ian@wright52.plus.com

Ian all my bikes have their guards acid etched after blasting then I use black stone chip the stuff they use on cars to rust protect panels not to be confused with underseal. Stone chip is really good stuff and and drys to a slight wrinkled finish which takes primer well and seals the rolled edge of guards against corrosion.My old A10 combo was used every day for work in all weathers for 8 years solid before I decided to rebuild it when the guards were blasted they were still good with only light corrosion around mounting holes.I am now restoring a Thunderbird this will get the same treatment..

Hi Dave...Thanks for that little bit of information...

For the last few restorations I have had everything powder coated before spraying. This one has now had the same treatment with a high zinc, powder coated base coat...

I've also been looking at various options along the lines you describe and will use one of them..Can you tell me the trade name of the stone chip you used?...Ian

email (option): ian@wright52.plus.com

Hi, Ian I use a Hammerite make used with a schutz gun these are 1 litre cans. Note I always use two pack paint but cant see a problem with this being sprayed on top of a powder coat base then a two pack paint applied.

Same as this Ebay listing

http://www.ebay.co.uk/itm/HAMMERITE-STONECHIP-STONE-CHIP-SHIELD-SCHUTZ-BLACK-1-LITRE-5092835-/261152342001?pt=UK_DIY_Material_Paint_Varnish_MJ&hash=item3ccde47ff1

I know it has become difficult in some places to find services for various coatings due to alleged environmental concerns, but if possible, I believe that all metal exposed to the elements should be zinc phosphated before applying etching primer. Using this process assures that the metal is corrosion protected in all of the most vulnerable places. Parts with internal folds and surfaces such as frames, forks and mudguards benefit the most. Originally, parts were factory Parkerized for protection.
Wade

email (option): iron_ariel@yahoo.ca

A restorer I know swears by POR15 aka KBS Coatings available from The Rust Shop, Milber Service Station, Shaldon Road, Newton Abbot. Can be sprayed, available in basic colours, bulletproof, pricey!

Rick

email (option): rick.howell@talktalk

Newton Abbot?...I can have a nice ride over Dartmoor and pick some up!...Ian

email (option): ian@wright52.plus.com

POR 15 applied with a brush is standard practice for me on every piece of metal I use.
The stuff is thinner than water so will flow inside of all the rolled edges & under rivets.

A few down sides
It is not UV stable so you have to top coat it
The brushes can not be cleaned
Requires a bare metal surface ( slightly rusted for best results )
Once opened it will go off in the tin so you need to buy small cans which is not economic

Good side
Lasts for hundreds of years and once cured can not be removed by any physical or chemical means unless it is irradiated with UV first.

email (option): wariron@tpg,com,au

I swear by WD40

seriously its great for the "barn find" type of machine. It can be sprayed, using the small tube that it comes with, into the smallest most inaccesible places like under the mudguards, into frame tubes etc. The rest can be wiped over with a rag sprayed with it. I've used it for years and never had any probs with it.

Try the INNOX version, much better than WD40, dose not completely dry out like WD 40 does so it leaves a small lubricating film behind, far better penetrating powers & oddly enough just as good as water dispersing.

email (option): wariron@tpg,com,au

ACF50. Expensive but affords rust protection for at least 12 months except on really exposed surfaces. As stated above, ideal for preserving original paintwork and penetrating nooks and crannies on new work (after painting).