Topic: Bright Zinc Plated Bolts > Dull Finish

[alanmac]

I had some of my original bolts and hardware plated at a local shop.  It was pretty much a disaster, that I wont go into.  Is there a way to change the shiny bright appearance to a dull finish?  Alan   

[Bob Gaines]

You might try a bath in vinegar or stronger acid. It may dull the finish on its way to eating off the finish. You will have to play with time in bath . It will also depend on strength of acid used.Obviously you need to try a sample first to see how that approach works. I use muriatic acid to strip zinc off of nuts and bolts for example

[J_Speegle]

Vinegar will strip off the zinc completely so either water it down for the bath or use very very short intervals in the bath. Another option would be a light acid wheel cleaner - the stuff made for non- clear coated rims. Spray it on and keep it moving - hands covered with rubber gloves will protect your hands. Don't let it dry on the surface

[alanmac]

Thanks for the input.  I tried vinegar before and it turned black, but watering it down and keeping an eye on the time might work.  I was wondering if a tumbler with some sort of abrasive in it could work? 

[jwc66k]

I was wondering if a tumbler with some sort of abrasive in it could work?

Look up "Phosphating 101" in "Processes, Products & Technique".
Jim

[alanmac]

Jim, I am not sure what you are suggesting. 

[jwc66k]

I am not sure what you are suggesting. 

a tumbler with some sort of abrasive in it could work?

Look up "Phosphating 101" in "Processes, Products & Technique".

Did you look?
Jim
Let me help - https://www.concoursmustang.com/forum/index.php?topic=4624.msg25789#msg25789

[alanmac]

Is this the key?  tumble in metal filings for a week; dip in kerosene; air dry for at least two weeks; Beer drinking is encouraged.

[jwc66k]

Beer drinking is encouraged.

Yes. While processing. I recommend a Brandy Manhattan (an off-road enthusiasts' preference), on the rocks, no bitters, no cherry, to be made and consummed at the end of a motor vehicle restoration daily cycle.
Jim
Picture attached of my tumbler stuff. It is slow, meticulous and effective. This one is from https://rocktumbler.com/thumlers/ Don't forget to "rinse" the metal filings off in kerosene. Don't use water. It causes rust.
The second picture is my vibrator (Eastwood, I think) but it is noisy and does not clean threads well. Plus the glass pyramids get stuck in the threads of nuts and between the head and washer of that type of screw.

[Bob Gaines]

I had some of my original bolts and hardware plated at a local shop.  It was pretty much a disaster, that I wont go into.  Is there a way to change the shiny bright appearance to a dull finish?  Alan   

Your vinegar is probably too weak of acid.  3-5 percent is typical household strength.  When I use muriatic acid it will not turn black .It bubbles quickly as it dissolves the finish . A finish on a bolt will typically completely dissolve  in 4-5 minutes (when it stops bubbling) .   If you use that I would suggest you will test starting with 5 seconds and moving up in 5 second increments checking for results. Of course use gloves and safety glasses.

[jwc66k]

I had some of my original bolts and hardware plated at a local shop.  It was pretty much a disaster, that I wont go into.  Is there a way to change the shiny bright appearance to a dull finish?  Alan   

Yes. There is a recent plating process called "dull zinc". It came about about 7 or 8 years ago. It is my understanding that some shops can't/don't do it. The results are "close" to cad plating.
Jim

[alanmac]

Does your plater have the dull finish process?  I only have 16 bolts.

[alanmac]

Thanks for the options.  I'll do some testing...

[rockhouse66]

My plater told me if I want dull zinc to find someone who does cad plating 

[Drew Pojedinec]

Not that I know anything about plating?.

There is really no such thing as ?dull zinc? plating. It came out in the 1920s when platers had very crude systems.
It?s just plating without brightener.

Plating without maintenance brightener is a pain in the butt.
I can understand why a professional wouldn?t want to do it for a few reasons.
One is that to do it for a few bolts wouldn?t make sense at all.
Plus the actual plating process is crappier.

If you want it to look dull dip it in a sealant. Generally speaking a sealant like I use and hot air drying makes the part come out dull and lifeless.
If that is too troublesome, just spray the chromated bolts with wd40 and hit them with some steel wool.