Author Topic: Zinc Plating. The good and the bad.  (Read 216 times)

Offline nairb

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Zinc Plating. The good and the bad.
« on: February 24, 2021, 02:38:54 PM »
For several years I have been Zinc plating those small(ish) items found on bikes.  Especially those old bolts that have the "S" or honda logo on the bolt head.  Usually with OK results.
The bigger items I take to the professional platers up the road.  And for little money they usually turn a batch around in a week.  All nice BZP. 

I have never taken a set of spokes to be done since the charge seems to be about a quid for each item.  In other words if I take 20 items its 20(ish) quid.  So 38 spokes with out nipples might be 40 quid or so.
So over the years I have plated up some 4 wheels worth of spokes - mostly with good enough results.  Along with dozens of bolts and other items.

I follow the same process each time.  I have renewed the electro-light once over the years.  Its cheap to get the zinc chloride etc off that auction site.

Now finally to the problem - I have 2 more sets of spokes to do.  Its 90 quid for a set of stainless spokes or its a lot of time and effort and little cost to re-zinc them.  They are NOT corroded.  Just poor finish and light rust in places.

So I strip the old zinc off with brick cleaning acid..... they fizz for a short while and wash in tap water etc.
They come out of the zinc process looking even and ok.  A wash in water then into the passivate and they end up looking reasonably fine and bright.  A good wash and dried off.  They look fine.  Just what I wanted................. except after a few days the zinc starts to bubble off.  Some of the spokes remain fine but a 3rd  or so need re-doing.  And maybe again also.

I know there are several variables at work here.  I have a small heater to keep the temp constant.  A meter to check the current from the 12v supply via a variable resistor.

Just wondering if the more experienced platers out there have a suggestion.  This diy plating can work quite well with effort.

Thanks
Nairb

cb550k3, cl450k5, re5m, xs650xs2, mt500, kettle, gt550 x2,  gt380

 

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