DIY Zinc Plating

[andeep]

Hi Guys,

For the people out there that have a DIY Zinc Plating Kit, how do you go about cleaning rusty nuts and bolts prior to plating?

I have contacted classic plating and they have said to use their Electrolytic Cleaning System to fully clean the material before plating. I was wondering if there is a more 'industrial' method of doing this such as using a strong acid? What do professional platers use to fully clean nuts and bolts?

Many Thanks,
Andeep

 

[KemppiFrog]

My hot dip platers use acid, as did my old electro platers. They hate paint and the HD outfit are fussy how much rust there is. I had to have some anchors sand blasted as they had been left out for a while after manufacture.

 

[Burdekin]

Hi Guys,

For the people out there that have a DIY Zinc Plating Kit, how do you go about cleaning rusty nuts and bolts prior to plating?

I have contacted classic plating and they have said to use their Electrolytic Cleaning System to fully clean the material before plating. I was wondering if there is a more 'industrial' method of doing this such as using a strong acid? What do professional platers use to fully clean nuts and bolts?

Many Thanks,
Andeep

Cleaning Solutions
Isopropanol IPA
Sodium hydroxide (caustic soda – heavy duty drain cleaner)
Hydrochloric acid (brick cleaner)
Tap water between each cleaning step.
Pre-Cleaning Process
If the part is already zinc plated, rusty or heavily soiled, do the following.
Clean parts in thinners to remove grease, underseal etc.
Clean part in hot water, washing up liquid and baking soda, then dry.
Soak the part in hydrochloric acid until the solution stops fizzing.
When the fizzing has stopped, all of the old zinc / cadmium plate will have been removed. Now wash the part in water. Inspect and check for rust. If there is rust on the part, put it back into the hydrochloric acid. Inspect every 30 minutes or so. Don’t leave it in any longer than necessary. Wash the past in water each time you remove it.
Once you have completed the above, lightly wire brush the part by hand. This will remove any residue from the process above. Again, wash in water. Now you can move to the Cleaning Process.
Cleaning Process
This is the important bit.
Wash part in Isopropanol IPA, then water.
Wash part in Sodium hydroxide then water.
Wash part in hydrochloric acid (max 2 minutes) then water.
If water will not bead on the job, it is clean. If water does bead on the job, clean it again. Look up the Water Break Test to get an idea of how to check surface cleanliness.
When water will not bead on the job, it is ready for plating.

 

[MattF]

If you try hydrochloric, (nasty stuff, as is the caustic, so be careful and use common sense around them), make sure the fumes don't get anywhere near any good metal. It'll rust things likes there's no tomorrow, by all accounts.

 

[andeep]

Thanks for the replies guys.

How does electrolytic cleaning compared to acid? One reason why I don't want to use acid as I don't want to damage the item being cleaned.

 

[droopsnoot]

I've got a passivated plating kit from Gateros, which reminds me I need to set it up again. I've cleaned stuff with either a citric acid dip, or electrolytic cleaning, depending on the size mainly. The citric acid costs a lot more than some washing soda to fill a bucket for electrolytic cleaning, so I usually only have a 1l jug of it.

When I bought the kit, I also bought some of their "special" pre-clean but I haven't used it yet. Some of the plating issues I had might well have been cured had I done so. The kit includes an "acid pickle" cleaning step, but they also have another recommended but optional one.

I've also recently tried phosphoric acid in the jug (in the shape of 'ph Down', sold for hydroponics applications) and Milkstone remover - much cheaper than phDown but less concentrated I think. Both work pretty well, phDown seems to remain active for longer.

I suspect (and the short piece on 'For the love of cars' the other night seems to support) that commercial platers have access to much stronger cleaning solutions than the rest of us.

 

[Mr shiney]

I blast mine in the small cabinet and then Polish on the wire wheel and finally the Polish wheel. They then go in alkaline cleaner and finally in the acid pickle.

With zinc plating the finish is only as good as the prep.