I bought a Raleigh Burner last year that needs a full resto. The steel rims were too far gone to polish up, so I took them to be stripped & re-chromed. The hubs also needed re-chroming. As burner spokes are a thicker gauge than standard spokes, I carefully removed them, put them to one side and polished the nipples up (took about 4 hours)!. The spokes were dull and had started to rust, so I took them to my local friendly chromer (Leigh metal polishers) who suggested that zinc plating them would be the best idea. A few weeks later I picked up my lovely shiny spokes, and took them, the rims and hubs to my local bike shop to get the wheels built up.
I went into the bike shop to check on their progress, but was told the spokes wouldn't screw into the nipples as the zinc plate had filled in the threads. As these spokes aren't readily available, I thought about a way to strip the threads to make them fit. I found out that most acids will dissolve zinc plate - some people use vinegar but it takes a while. I couldn't wait that long, so I decided to look for some sulphuric acid (car battery acid), which supposedly works better and faster. After a few calls to car parts/motor factors shops, I found a local one that stocked the stuff (£9 for decent sized bottle). I also found out that bicarbonate of soda (baking soda) can be used to neutralise the acid once you're done. So I went to the supermarket and bought:
A starbucks coffee drink in a glass bottle to use as a suitable container
Baking Soda, which I mixed with water
Washing up gloves (pink of course) as seconds skin to my heavy duty workmans gloves
De-ionised water to prevent unwanted reactions - probably didn't need it, but what the hell
a container to neutralise the acid once done
a funnel
nice shiny zinc plated spokes
with threads that were useless as full with zinc
sulphuric acid
I used a roughly 50/50 mixture of acid and water. Just enough to cover the spoke threads
spokes then went in - I did 72 spokes in 2 goes, as the neck of the bottle was too narrow to do them all at once. I wore goggles and 2 pairs of gloves throughout the process
the reaction was instant. Fizzing nicely, with a bit of heat given off that could be felt through the bottle. An exothermic reaction I seem to recall from my GCSE chemistry days
It took about 20-25 minutes for the zinc to come off. I removed the spokes, dunked them in the baking soda solution, then used a small wire brush to remove any stubborn bits of zinc. I then dried the spokes and gave them a very quick polish with some peek to remove any stains.
and here you go - the spokes now fit and screw into the nipple
I'm not sure if sulphuric acid will remove other forms of plate such as copper, nickel or chrome. I don't think so, and some metals/processes can be dangerous/harmful, so take your parts to the experts if you aren't sure.
