Parts prep for plating

[230slhouston]

Hi All,
I am in the process of cleaning parts for plating. I am cleaning this in an alkaline solution. Cleaning out pretty well. What else should id do before sending to the plater?
Do I need a vibratory tumbler? Suggestions?

Thanks
Maistran

[wwheeler]

The simple answer is the cleaner they are when you give them to the plater, the better the results. These look like they need a lot more prep work to me. At minimum, you must remove all of the grease, oil and dirt. If not, they may not get them perfectly clean and you will have parts with defects on them.

Of course there are several techniques, but to start, I have used this  https://www.homedepot.com/p/ZEP-5-Gal-Industrial-Purple-Degreasers-ZU08565G/100619267 They sell a gallon of it at the bog box stores. It is strong stuff and try not to get it on your hands. Use a plastic tub (not metal) to put the parts in. First and in the bottom, put a decent sized piece of thin aluminum like from a cornbread loaf tin. Next go the bolts and then fill with the degreaser at full strength. The aluminum will react with the solution causing much fizzing and will agitate the grease away. I discovered this by mistake, but works fantastically. The aluminum is a sacrificial element that cause the fizzing. That will remove grease and oil.

If you can abrasive blast, that would be preferred. If not, wire brushing, hand sanding or a vibratory tumbler will work. Harbor freight sells a cheap one that works ok. The platers will remove any plating left on the hardware at this point. Just remember, the more work you do upfront, the better the parts will turn out.

[230slhouston]

Thanks Wallace. I am using the industrial purple degreaser. they come out pretty clean. I think i will tumble them as well. Invest in the one from harbor freight.

[johnk]

Go with the lareger unit at harbor freight. You cant fit much in the smaller one without burning it out. Keep your receipt as you can exchage it for a new one if you burn it out.

[ja17]

I like soda blasting of mechanical parts. Use a warm water rinse afterward to dissolve the soda away. Abrasive blasting with sand, oxides or even beads can be fatal on engine and transmission parts.

[Peter]

De-rusting is also important, at least that was it for the plating company I used. 
After degreasing, I put the parts a day in hydrochloric acid to de-rust, then rinse well with warm water.
then I sprayed some WD40 over it to prevent it to rust again before treatment
The WD40 was taken of in the cleaning process of the plating company.   

[Shvegel]

Phosphoric acid from your local Home depot works well as a derusting step.  I use it full strength and rinse with clean water.  The phosphoric acid imparts a slight phosphate coating on the parts and helps to keep them from re-rusting.

https://www.homedepot.com/p/Klean-Strip-1-gal-Concrete-Etch-Metal-Prep-Rust-Inhibitor-GKPA30220/100406369

[hkollan]

The plating companies I have used over the years all use a pre-plating cleaning process involving some sort of acid bath.  Checking with the plating company first before
getting involved with nasty acid stuff at home, might be worth while.

Hans K

[stickandrudderman]

Indeed,
I take them off the car and hand them to the plater. If you really want to go bananas you can have the parts cleaned and polished first but you'll get a finish that is only meant for show cars.

[230slhouston]

Thanks folks for the ideas.

[Alex D]

Unless you are going for show car quality and are not planning on driving the car much, I would not go to crazy, after a 2,000 miles of driving the "new shine" factor starts to loose its luster. 

[Rhinkel]

Be careful with the use of acids to clean your bolts and hydrogen embrittlement.  You ever twist a bolt off and the inside of the bolt looks grainy? That's the result. Cleaning and plating can cause this on many parts and oftentimes we bake off the parts to remove this risk. Ask your plater about it.

[wwheeler]

If you use acid, yes be very carful. Always add acid to water and NOT the reverse. Google it for more safety info.

When I use muratic acid to clean hardware, it is simply to remove the old plated surface after the hardware is already clean. That reaction happens in a matter of seconds and not nearly enough time to do damage to base metal of the hardware. Anymore time than that is risky.

Spring steel is a different matter. Yes, Hydrogen embrittlement can make spring steel parts brittle and prone to failure. Platers do have a seperate treatment for that and you should seperate parts made of spring steel. Also I would not advise reusing split lockwashers. They are cheap, readily available and will frequently break after plating. There is just no justifiable reason to have those re-plated.