Ducati.ms - The Ultimate Ducati Forum banner

1 - 20 of 21 Posts

·
Registered
Joined
·
505 Posts
Discussion Starter #1
SO... bit of a problem discovered after unwrapping two Superbike forks from long storage. In the darkest chapters and verse of Murphy's Laws and Corollaries, Volume 3, there exists the clause:

"When said event gone wrong is left unmitigated, whether through malfeasance, tort or gross negligence, said Wrong shall increase assessed Damages and shall accrue at a compound rate until collateral damage shall commence and ultimately lead to catastrophic failure and loss."

Said collateral damage shown in the attached images is a dark gray chemical deposit, hardened in some way, left underneath powdery deposits left on the fork from an exploded dry cell AA-size battery. Somehow, this evil device worked its way into the well-wrapped in Kraft paper and bubble wrap, packed tightly inside a carton, which was stored in dry garages for several house moves.

If there is a chemical engineer amongst us, or other really smart person, how to remove said hard-shell chemical coating from the aluminum fork tube, which has a clear anodized finish, I assume. I have determined that said deposits are additive to the surface, so can be removed. If I can find an equal, opposite chemical reaction from that which deposited this hard substance, the hope is that the aluminum underneath won't be scratched as from a mechanical removal of the deposit.

Any advice in the quest to save this fork's down tube would be greatly appreciated.






IMG_6424.JPG
IMG_6425.JPG
IMG_6425.JPG
 

·
Come in Spinner :)
Joined
·
7,547 Posts
Caustic soda will remove all the crap as well as the anodizing quite quickly.
I use it as a quick dip to remove "The Jeepney" look from parts that have that flashy gold finish.
That stuff has eaten right through the surface finish and actually eaten into the base alloy so some heavy duty re-finishing will be involved
 

·
Registered
Joined
·
505 Posts
Discussion Starter #4
Thanks Davo. Pleading ignorance here, so caustic soda sounds like the nuclear approach of last resort.. Plan B of sorts.

Anybody venture a guess as to what that chem deposit is that was left from the battery puke?
 

·
Come in Spinner :)
Joined
·
7,547 Posts
You will have to get mechanical to remove the damage.
 

·
Registered
Joined
·
505 Posts
Discussion Starter #7
eBay is my last option. No time for more projects. If I can remove this crap chemically, that'd be best.

So, I've soaked it in WD40 to soften it, loosen it from the base material, and in hopes to halt the chem reaction if still active. I think it's long done.

Alkaline battery geek stuff:
https://www.powerstream.com/why-do-batteries-leak-white-stuff.htm ..seems legit, so lets go with it:

"Alkaline batteries are very similar to carbon zinc batteries. They use manganese dioxide and metallic zinc as the reactive materials, but they use an alkaline potassium hydroxide solution for the electrolyte instead of the mildly acidic ammonium chloride. The reaction products are manganese oxide and zinc oxide with by-products of manganese hydroxide and zinc hydroxide. So the white residue consists of manganese oxide, zinc oxide, potassium hydroxide, zinc hydroxide, and manganese hydroxide. Soon after oozing out, the potassium hydroxide reacts with carbon dioxide in the air to form potassium carbonate. Again, none of these chemicals is toxic, and all can be used in fertilizer.

..The KOH is very soluble, but the potassium carbonate isn't so much, which is a test to see if the reaction has occurred. In a flashlight the ingress of CO2 is slow, so the KOH has time to corrode the innards of the flashlight."


Since my forks underwent this abuse over a long time, I guess the KOH was converted by CO2 in the air into K2CO3, potassium carbonate - which is white. My stuff is medium gray. Further research advised that K2CO3 reacts with aluminum. So what I'm seeing as the tough, dark gray deposition seems to be the result. Cant find info on it. As its chalky if chipped off with X-Acto blade, vinegar and gentle abrasion may remove it and uncover any damaged base material. Seems the base material aluminum may have been eroded in the reaction.

Going after it with vinegar or lemon juice, since the deposit is alkaline, along with a toothbrush. Stay tuned.
 

·
Premium Member
Joined
·
4,800 Posts
You won’t remove anything. Caustic soda will remove the anodising. What has happened is the acid from the battery has eroded the anodic finish and then eroded the aluminium. Can’t be fixed. Sorry to be the bearer of bad news. Do a scrape with a razor, that’ll tell you if it’s only affected the surface.
 

·
Registered
Joined
·
484 Posts
I’m going with x here except it’s the alkali from the battery (KOH) not an acid 😉
It’s corroded your ally into Potassium Aluminate of some form. This is an oxide or a type of “rust” of potassium and aluminium...
You might be able to dissolve this with use of a strong acid - it’s been so long since I did any chemistry I can’t remember which actual alumimate is formed nor their stabilities but it may also cause more harm. Either way you have sustained some damage and I’d be at this with a mechanical action like a cup brush to assess the depth of the corrosion...
 

·
Registered
Joined
·
381 Posts
If it is any help, I have a just-about mint set of 999 Showa forks sitting in my loft which I've been planning to sell. I'm in the UK, but if you decide to replace and can't get hold of any locally, drop me a line.
 

·
Registered
Joined
·
505 Posts
Discussion Starter #12
I’m going with x here except it’s the alkali from the battery (KOH) not an acid 😉
It’s corroded your ally into Potassium Aluminate of some form. This is an oxide or a type of “rust” of potassium and aluminium...
You might be able to dissolve this with use of a strong acid - it’s been so long since I did any chemistry I can’t remember which actual alumimate is formed nor their stabilities but it may also cause more harm. Either way you have sustained some damage and I’d be at this with a mechanical action like a cup brush to assess the depth of the corrosion...
and... we have WINNERS in two categories for the Chemistry Prize.
1st Prize, Academic Chemistry - Neil66! I*

2nd Prize, Shed Chemistry - X and Davy!*

*All prizes payable in pints in person only, no coupons, internet or mail redemption. All rights reserved, whatever that means.

As X said, for the thick build-up to be there, there needed to be a reaction to the base metal. The anodized coating seems to be toast. the battery alkali leakage also reacted with CO2 in the air to create the dark gray substance that destroyed the fork tube. Wonders of Nature never cease.

Anywho, as an update, I have used a combo of overnight vinegar poultices and abrasion using plastic scrub pad to gently remove the chemical build-up. It is now down to the point where silver is showing through. Next up, stronger acid- lemon juice. Plan B: Turn the fork tube so the discoloration faces the triple clamp and wheel and she's good to go for a track bike.
 

·
Premium Member
Joined
·
4,800 Posts
Good to see you’re on top of it. Give the area the BEST clean and use a ph neutral is slightly acid wash to clean the best you can. Most modern coatings (read paints) don’t like alkaline surfaces. Abrade the bare metal as best you can the seal the offensive area with some moisture hardening paint with a small artist brush. Not to thick, you only need a thin film. Tomorrow I’ll post up pics of what happens to theses Ducati forks that have breaks in the anodic surface. Not pretty.
 

·
Registered
Joined
·
505 Posts
Discussion Starter #20
976795


after soaking for a week in the tightly wrapped paper towel poultice saturated with white vinegar that was wrapped tightly in plastic wrap to keep it in contact with the material .. the encrusted build-up had softened up nicely.

Then I removed the remainder of the build-up with ease using a drill-mounted scuff ball.
976796


The exercise worked as planned, and X is right, the clear anodized coating was eaten through. Will add a bit of clear coat to seal the base metal from the atmosphere, then I guess I'll maybe keep for track forks for my 996, or sell them as such.

Thanks for the feedback gents, it turned out well as could be expected.
 
1 - 20 of 21 Posts
Top