Plating at home

Where do you get HCL? Is pool Muriatic acid from hardware store good enough?

katit wrote: Where do you get HCL? Is pool Muriatic acid from hardware store good enough?

Muriatic acid = HCl

scubaanders wrote: Ok so let’s look at it from a scientific perspective.

Lots of great info here! Fantastic.

Personally, I use regular water for all but the last dip. Even though distilled water is cheap enough I always seem to run out and I'm too lazy to go to the store all the time.

Regarding the chromate dip time, I find that the color (yellow anyway) gets too deep unless the dip time is quite short (20 seconds or thereabouts gives the right color when using Caswell's chemicals.) When using the Blue (clear) chromate it dulls out the finish if you leave it in too long so I sometimes skip this step.

Nessism wrote:

katit wrote: Where do you get HCL? Is pool Muriatic acid from hardware store good enough?

Muriatic acid = HCl

Yeah. But look at what HD sells. They say it's 25-35% with exact percentage being "trade secret". There is other "Green" kind - which is not clear what it is and if it's good for our use. Also, this is from internet: "Muriatic acid is a form of hydrochloric acid, which has a pH of about 1 to 2. The only differences between hydrochloric acid and muriatic acid are purity—muriatic acid is diluted to somewhere between 14.5 and 29 percent, and often contains impurities like iron"

I am not chemist so I don't know if pH difference or % make any difference for us. Last time I used/tried muriatic acid from store it did work on rust removal. Just trying to get as much details as possible at this point.

Nessism wrote: Ok so let’s look at it from a scientific perspective.
Regarding the chromate dip time, I find that the color (yellow anyway) gets too deep unless the dip time is quite short (20 seconds or thereabouts gives the right color when using Caswell's chemicals.) When using the Blue (clear) chromate it dulls out the finish if you leave it in too long so I sometimes skip this step.

From what I researched (youtube videos mostly) - yellow is basically "what you want". Can be from 10 seconds to a minute depending how yellow you want it to be. The guy was dipping for 10 seconds and then checking if he likes it.

Lots of good info so far.

Still curious on the cost comparison. It seems a pretty decent setup can be had for around $300. How does this compare to most in having parts done by a plating shop? Not looking to have engine covers or anything like that plated, just nuts, bolts, axle shafts, chain tensioners, etc.

I had almost exactly the item you mentioned done for less than $200. That includes shipping and Vapor blast.

katit wrote:

Nessism wrote:

katit wrote: Where do you get HCL? Is pool Muriatic acid from hardware store good enough?

Muriatic acid = HCl

Yeah. But look at what HD sells. They say it's 25-35% with exact percentage being "trade secret". There is other "Green" kind - which is not clear what it is and if it's good for our use. Also, this is from internet: "Muriatic acid is a form of hydrochloric acid, which has a pH of about 1 to 2. The only differences between hydrochloric acid and muriatic acid are purity—muriatic acid is diluted to somewhere between 14.5 and 29 percent, and often contains impurities like iron"

I am not chemist so I don't know if pH difference or % make any difference for us. Last time I used/tried muriatic acid from store it did work on rust removal. Just trying to get as much details as possible at this point.

I bought muriatic acid from the hardware store a good while back and cut it about 5:1 water and it removes zinc plating pronto.

I didn’t know you guys wanted to fall down the chemistry rabbit hole, so let’s take it a step further.

Acids
The strength of an acid is measured in acid dissociation constant (Ka) (acidity) and can be seen as how corrosive the acid is.
Here are a few examples of acids from very too least acidic.

Name	Formula	Acidity	Popular name
Perchloric acid	HCIO4	-15	Super acid
Hydrocloric acid	HCl	-5.9	Muratic acid
Sulfuric acid	H2SO4	-2.88	Vitriol
Nitric acid	HNO3	-1.4	Spirit of niter
Phosphoric acid	H3PO4	2.2
Citric acid	C6H8O7	3.13
Acetic acid	CH3COOH	4.76	White wine vinegar

But it’s not always a good idea to use the most acetic acid as it will not only eat up your rust, it will eat the metal as well. Therefor most acid are diluted I water to make them less aggressive.
a quick dip in 30% Hydrochloric acid quickly dissolves rust, where as it will take hours in acetic acid.

For instance when I derust gas tanks I use 30% Hydrochloric acid and if the tank is heavily rusted I leave it in the tank for 10min, max 5min for lightly rusted. Where as if I should use any of the weak acids it will take up to 24 hours until the tank is clean.

Strong acid also have a flip side in that the surface it leaves is very prone to flash rust and has to be handled in order to prevent that.

I personally use 30% hydrochloric acid that I buy in hardware stores where they sell masonry supplies as it is used to clean concrete floors before they are painted.
They usually also sells something they call “Tile and clinker cleaner” which is used to remove cementitious adhesives and grouts from tiles and clinker. These products usually contains up to 30% Phosphoric acid and are excellent to use to remove rust under more controlled forms.

Phosphoric acid has one more nice feature, when the concentration is <5% it reacts with steel to form Iron(II) phosphate, which acts as a rust prohibiter and is a good way to reduce flash rust after derusting with a stronger acid.

Distilled water.
Where I live we have excellent tap water that is sourced from one of our great lakes.
The tap water contains hardly any Iron or calcium carbonate, with our climate we use minimal amounts of chlorine and there is basically no fallout of copper from the water pipes. Therefore I also use regular tap water for al cleaning baths and only use distilled water when diluting chemicals.

But if you live in an area with iron, calcium carbonate or where the water works adds a lot of chlorine I recommend that you use distilled water. Otherwise you will get discoloration on your hardware.

Passivate dip times.
In order to passivate the zinc just a 5 second dip is sufficient, but when using Yellow, Olive drab or especially black passivates I have found that I will have to dip the hardware for up to 5 minutes in order to get the coloration I want.

Note!
And always when handling acids, remember! Alice in Wonderland (Acid in water). Always pore the acid in to the water, NEVER the other way around as it can start a boiling reaction and send the solution your way. By the way, use personal protection and I am not talking about your S&W.

/Anders

Btw, to anyone interested. I placed order with Caswell about 2 weeks ago. Not shipped. No response on ETA.

Got my kit! Realized I need a heater. Read some people use aquarium tank heaters. Can anyone point to heater they use and how does it work?

katit wrote: Got my kit! Realized I need a heater. Read some people use aquarium tank heaters. Can anyone point to heater they use and how does it work?

I use an aquarium heater but can't recall the brand. I also use a thermometer.