Citric OK for pre plating prep?

[JOEPRO]

I am totally new to zinc plating. It was VERY hard to find a kit who would post to NI. Eventually this more expensive kit was posted and should arrive monday:



I see on you tube people use Muriatic acid to clean their bolts at 10% or so dilution "readily available from your local hardware store". (Yanks!)

I think if I go asking for pure acid locally ill get arrested.

Is that a thing or can I use warm Citric acid for the prep stage?



Finally, I presume I need to buy a 5 gallon drum of distilled water for this kit as there is no real alternative is there?

Its items like this I want to yellow zinc plate



These were blasted and left overnight in citric. I will also wire wheel buff them to shine before plating.

 

[JOEPRO]

PS for anyone interested I can make a you tube video on using this kit if it may be useful let me know and ill do that

 

[Seadog]

Muriatic acid is Hydrochloric acid, HCL - https://apcpure.com/product/hydrochloric-acid-10/HCL10-G?gbraid=0AAAAADk1sy56843ZomB2_yie4bRm-4ox8

 

[Ross365]

I think citric should be perfectly OK for this; it will wash off in the distilled and leave nothing behind. By contrast, hydrochloric tends to leave chloride ions behind, which adsorb strongly on metal surfaces and which water alone may not remove. Chloride ions are wonderful at initiating corrosion. Bottom line, citric won't be as fast, but may well be the better option.

 

[JOEPRO]

Muriatic acid is Hydrochloric acid, HCL - https://apcpure.com/product/hydrochloric-acid-10/HCL10-G?gbraid=0AAAAADk1sy56843ZomB2_yie4bRm-4ox8

Thanks but they dont post to NI. 90% of sellers won't

 

[Seadog]

I'm not sure that I'd be allowed a gallon on the plane when I fly in next week

 

[Seadog]

You can't buy brick acid or pH corrector in NI?

 

[Misterg]

I use brick cleaner for a pre-plating etch. (It's usually 10% hydrochloric acid - check SDS to be sure).

I'm not sure that citric acid would be aggressive enough to clean the surface pre-plating.

My process:

Clean / de-rust in magic citric acid / sodium hydroxide mixture;
Wire brush to shine;
Hot, alkaline degrease;
Rinse;
Etch in brick cleaner (10% HCl) for about 30 seconds;
Rinse;
Plate;
Brief etch in diluted brick cleaner (2% HCL) until bubbles appear
Passivate;
Rinse.

I use an alkaline plating process which I suspect is different to the kit (follow their instructions), but prep should be the same.

Thread 'Alkaline Bright Zinc Plating DIY'

Dec 1, 2025

As per the other thread, I've been using alkaline zinc plating to freshen up some bits and bobs from my rusty MX5.

It is an electroplating process, but unlike 'normal' electroplating, the anode is plain steel in a zinc rich electrolyte. The zinc level is kept topped up by having a 'zinc generator' (a chunk of zinc in electrical contact with steel) in the solution. There is no electrical connection to this.

Advantages stated for this (over conventional plating) are a greater 'thow' (less 'line of sight' effect), more uniform coating thickness and a more ductile coating layer. I went with...

• Misterg
• Replies: 18
• forum: Paint, Metal Coatings and Media Blasting

• 
• 
• 

 

[Ross365]

I use brick cleaner for a pre-plating etch. (It's usually 10% hydrochloric acid - check SDS to be sure).

I'm not sure that citric acid would be aggressive enough to clean the surface pre-plating.

My process:

Clean / de-rust in magic citric acid / sodium hydroxide mixture;
Wire brush to shine;
Hot, alkaline degrease;
Rinse;
Etch in brick cleaner (10% HCl) for about 30 seconds;
Rinse;
Plate;
Brief etch in diluted brick cleaner (2% HCL) until bubbles appear
Passivate;
Rinse.

I use an alkaline plating process which I suspect is different to the kit (follow their instructions), but prep should be the same.

Thread 'Alkaline Bright Zinc Plating DIY'

Dec 1, 2025

As per the other thread, I've been using alkaline zinc plating to freshen up some bits and bobs from my rusty MX5.

It is an electroplating process, but unlike 'normal' electroplating, the anode is plain steel in a zinc rich electrolyte. The zinc level is kept topped up by having a 'zinc generator' (a chunk of zinc in electrical contact with steel) in the solution. There is no electrical connection to this.

Advantages stated for this (over conventional plating) are a greater 'thow' (less 'line of sight' effect), more uniform coating thickness and a more ductile coating layer. I went with...

• Misterg
• Replies: 18
• forum: Paint, Metal Coatings and Media Blasting

• 
• 
• 

What material are you working on; what is the passivate step (most commonly, 25% nitric applied to stainless).

 

[Misterg]

What material are you working on; what is the passivate step (most commonly, 25% nitric applied to stainless).

Nuts 'n' bolts & steel pieces.

I use the Chronos clear/blue passivate solution. No idea what's in it!

 

[JOEPRO]

Nuts 'n' bolts & steel pieces.

I use the Chronos clear/blue passivate solution. No idea what's in it!

This although ill also be using their kits included yellow passivate

Pardon our interruption...

 

[Misterg]

This although ill also be using their kits included yellow passivate

Pardon our interruption...

I couldn't get on with their yellow. It didn't seem to do anything, but maybe because I was using a different process (see the thread I linked to above if interested in details). I'd be interested to see your results.

 

[Ross365]

Nuts 'n' bolts & steel pieces.

I use the Chronos clear/blue passivate solution. No idea what's in it!

According to Google, the Chronos blue solution contains trivalent chromium, deemed to be safe, unlike hexavalent chromium... something new everyday .

 

[Agroshield]

I do not know the answer to this, but does the 'salt' (i.e. chloride in HCl) need to have any compatibility with the salt in the plating solution?