Caswell Plating

[jfa.series1]

23 minutes ago, newtonhubcap said:

jfa.series1 mentioned a commercial playing shop? Do you remember the name of the shop?

Sent from my SCH-R970 using Classic Zcar Club mobile
 

I've used Texas Precision Plating in nearby Garland TX.  Find them here: http://www.texasprecision.net/

[Namerow]

22 hours ago, jfa.series1 said:

I've used Texas Precision Plating in nearby Garland TX.  Find them here: http://www.texasprecision.net/

I had a quick look at the TPP website and found some interesting info (assumed accurate) about zinc and cad plating and chromates...

" Zinc plating is a soft, decorative, corrosion-resistant finish. Zinc protects the substrate by sacrificing itself and thus corrodes before the base metal. This means that zinc will protect even if the zinc coating sustains minor damage, such as scratches or small punctures because of the galvanic protection of the zinc; however, the zinc coating can be attacked or dissolved by ordinary liquids such as soft drinks and vinegar. The ultimate corrosion resistance of zinc is dependent on the thickness of the coating. To increase the corrosion-resistance of the zinc, a conversion coating is usually added. The primary use of chromate finishes on zinc is to retard or prevent the formation of white corrosion products on zinc surfaces."

'Attacked or dissolved by ordinary liquids such as soft drinks or vinegar' !!!    I'm going to try this on one of the parts that I've already plated (poorly) to see what happens.

 

Also:

It looks like the max. target thickness for commercial/industrial zinc plating is 0.001".

 

TPP has the following to say about cadmium plating (which they apparently still offer):

" Cadmium plating is generally bright silvery white. Supplementary treatments for type II can be golden. iridescent, amber, black, or olive drab. The corrosion resistance is very good, especially with the type II finish. Cadmium plating is still the preferred metal over zinc, in the aerospace industry.  This is partly due to its excellent adhesion properties for painting, and it can't be stripped off as readily as zinc. Cadmium is excellent for plating stainless steels that are to be used in conjunction with aluminum, to prevent galvanic corrosion.  TPP offers the following chromate conversions for cadmium: Clear, Yellow, Black and Olive Drab.  Parts with a hardness greater then Rc-40 shall be stress relieved prior to cleaning and plating, and should be given a hydrogen embrittlement relieve post bake."

 

Interesting that there's no mention of post baking (re hydrogen embrittlement relief) in their discussion of zinc plating.

[Careless]

FWIW... ZTherapy bakes their plated parts twice when doing carb rebuilds. My industrial plater just leaves them in a spot with a lot of sunlight.

Also, most cadmium plating i've seen is kind of ugly. almost powdery- even on the yellow stuff. not quite as "blingy". could just be the ASTM spec for the parts I've seen, but from what I've been exposed to- zinc plating looks nicer.

[Namerow]

Well, third time's a charm, it seems.  After two lengthy and unsuccessful adventures with a DIY electrolyte set-up, I finally spent the money and bought the Caswell chemicals.  It took me almost full day to create a new set-up...

• I created all-new baths (distilled water, muriatic acid, MEK solvent, Caswell electrolyte, Caswell blue chromate & Caswell yellow chromate). 
• Every container was wiped down with alcohol before use, to make sure and manufacturing residue, fingerprints, etc. were gone.
• I also replaced my wire wheel (brass) with a new one, just in case the old one had acquired any kind of contamination.
• The acid bath was mixed at 1 part acid to 4 parts distilled water 
• Electrolye and chromate baths were created according to the directions on the Caswell packaging (I didn't buy their manual).and added new ones for the electrolyte and the two phosphates)
• I used a fresh, single hoop of Moss-Boss zinc foil
• I added 1/2 teaspoon of Caswell's brightener liquid before getting started
• No heating used for the acid bath, nor for the two chromate dips
• My detergent bath consisted of a 4-qt crock pot full of distilled water, to which I added 400ml of liquid ammonia and a shot of dish detergent.  I kept this at about 100 degrees F.  Parts were scrubbed with a toothbrush, then rinsed off in a distilled water bath.
• The electrolyte bath was kept heated at between 100 - 110 degrees F during plating, with constant agitation using an aquarium bubbler.  I pre-heat the solution with a hot water tank heating element, then remove the heater before I start plating.  I started at 110 degrees.  The temp dropped to about 100 degrees over the plating period.
• Plating current was set based on 140mA per sq.in. of part surface.  I ran the part for 20 minutes, turning it 90 degrees at the 10-minute mark.

I wasn't actually ready to get started with my first part (a brake line clip from the engine compartment) until about 3:00 Sunday afternoon.  The part looked good coming out of the zinc plating step -- full coverage, dull light grey, no burning, no visible edge or corner effects.  It got a quick swish in a distilled water bath, then into the blue chromate for a 60 s. dip.  After that, it went directly (no rinse) into the yellow chromate dip for a 15s dip.  Then a quick rinse with tap water.  Then a 1 min. blast with a blow drier (running on HI heat).

I can't tell you what a relief it was to see the part emerge like this...

I'll post some pictures of my set-up later, along with some additional comments about settings and running multiple parts.  I haven't tried any large items yet, so that remains an unknown.

[Patcon]

Much better!!!!

[grannyknot]

Thumbs up! More pics!

[Namerow]

As promised, here are some pix and comments about my plating set-up...

Electrolyte Bath

Although a 3-gallon set-up would be great, that was going to push the cost of the Caswell 'Part A' and 'Part B' chemicals pretty high, so I opted for the 1.5-gallon set-up instead.  That meant doing some head-scratching about bucket sizes and shapes, so as to get the most out of the fixed, 1.5-gallon fluid volume. I looked at three possibilities:  5-gallon pail, 2-gallon bucket, and std-issue dishwashing bowl.  I filled each with 1.5 gallons of water and then measured the resulting depth.  The floating bottle caps give you an idea of the results.  While the 5-gallon pail gives a couple of extra inches in diameter, it also produces a relatively shallow bath depth.  In the end, Mr. Happyface won.  It gives me a bath depth of about 9" and a diameter of about 10".  The dishwashing bowl is what I propose to use for plating bigger parts (haven't tried it out yet).  Note: I cleaned all of the bowls in advance (wiped down with alcohol) to make sure there was no parting compound or other manufacturing residue on the inner surfaces.

The Caswell electrolyte chemicals consist of a bag of lumpy power and a jar of liquid.  They need to be pre-mixed, after which you add 1.5 gallons of (distilled) water.  I used the 5-gallon bucket to do the mixing.  The Caswell 'Part A' powder also contains a lot of big white chunks of stuff (metal salts?).  The chunks eventually dissolves, but not right off the bat.  Before adding the Caswell 'B' liquid to the Caswell 'A' powder, I broke down all of the powder lumps (not to be confused with the chunky stuff) and picked out a few suspicious-looking bits of small stuff that didn't look like they belonged.  After adding the 'B' liquid, I used a (clean) spoon to mix the two together (creates a watery paste) and then I added the distilled water.  I mixed the water in thoroughly, using a paint mixing attachment (pre-cleaned with alcohol) in my cordless drill.  The result is a kind semi-opaque, brownish liquid (which eventually turns clear).  I did all this mixing on a Saturday evening and just put the lid on the bucket before calling it a day.  Not sure whether the white chunks had fully dissolved at that point, but when I came back to the job the next day, the mixture had turned clear brown and there was nothing at the bottom other than a bit of undissolved debris...

I poured the liquid into another (clean) 5-gallon bucket, using a coffee filter to get rid of the debris.  Then I poured the filtered liquid into Mr. Happyface.  More details and pix tomorrow.

[Patcon]

@Namerow

Have you done any more plating lately?

Also I have a favor to ask if you can come up with a way to do it. Can you test the Ph in each one of your tanks? I added some water to my blue chromate tank because it looked low and now it seems to do very little to plated hardware. I am wondering if I drove the Ph too high. Since yours tanks are reasonably fresh I was hoping to use those as a target for the Ph of each of my tanks. They make digital Ph meters or if you have some test strips they would work too...

[240260280z]

I'll be in the fray soon!  Just got a 30V 5A Power supply and vibratory tumbled all of my extra hardware.  Now to open the Caswell kit that I bought way back in 2012..... vintage plating.

[Patcon]

2 hours ago, Blue said:

vintage plating

that's funny!

[Namerow]

2 hours ago, Patcon said:

@Namerow

Have you done any more plating lately?

Also I have a favor to ask if you can come up with a way to do it. Can you test the Ph in each one of your tanks? I added some water to my blue chromate tank because it looked low and now it seems to do very little to plated hardware. I am wondering if I drove the Ph too high. Since yours tanks are reasonably fresh I was hoping to use those as a target for the Ph of each of my tanks. They make digital Ph meters or if you have some test strips they would work too...

I did complete a second round of plating last weekend.  Things turned out well -- which was a relief, because my first session had run into trouble -- some kind of surface contamination on the last few parts I tried (might have been residual WD-40 that I'd used to keep the parts from rusting while were sitting around). 

Before starting the 2nd session, I refreshed all of my distilled water baths, made a fresh batch of acid, double-strained the electrolyte (you never know), and made fresh batches of detergent bath and yellow chromate dip.  I cleaned the inside of all of the bath containers with alcohol, too.  The problem parts went back into the blasting cabinet before the cleaning and plating was re-attempted.  I was not able to refresh the blue chromate dip because Caswell only gives you enough base material to make a single batch (unlike the yellow chromate, where they give you enough to make several baths ).  I think that the renewed blasting was what actually saved the day... but I wasn't going to take any chances with the baths.

Although I've certainly thought about it, I have not yet picked up a pH meter.  If I can find one at a plant nursery tomorrow that doesn't cost an arm and a leg, I'll be happy to try to help you out. 

FWIW, my blue chromate dip was mixed according to the instructions on the side of the Caswell bottle and it never seemed to produce as deep a blue tint as your photos suggest you've been getting with yours.  Following the instructions, I ended up with about 1/3 of the bottle's contents unused.  Maybe you used the whole bottle?   My point is that my blue chromate dip has produced pretty good results (to my eye, anyway), both on its own and as a pre-dip prior to the yellow chromate bath.  Maybe you should test yours on a single part in its now 'diluted' form to see if it might still produce an acceptable result?

BTW, I actually like the results produced by the blue chromate dip about as well as I like the yellow iridescent look produced by the combined blue/yellow dips.

I'll post some more pictures and comments this weekend.  I also made a chart of surface areas and start-off amperage settings for each of the parts that I've plated.  I'll try to post that, too.  Might save Blue and others a lot of measuring and calculating time.

[Namerow]

3 hours ago, Blue said:

I'll be in the fray soon!

My #1 caution (as others have said before me):  Your parts need to surgically clean. 

• All of the cleaning steps -- blasting/tumbling, acetone or MEK solvent wash, hot detergent wash, acid pickle, and distilled water rinses between each of these cleaning steps -- should be considered mandatory. 
• Wear nitrile gloves to keep finger oils of the parts.  Clean the nitrile gloves with alcohol before you touch anything.  Re-clean them or replace them regularly. If you stop to scratch an itch or have a snack, clean the gloves afterwards.
• Clean all of your bath containers with alcohol before you add the fluids. 
• Filter the Caswell electrolyte bath through a clean/new metal coffee filter before you use it. 
• Use a fresh wire or fibre wheel on your grinder/buffer (or Dremel) and keep it away from any oily parts.  A contaminated wire wheel will 'burnish' the oil contamination into your part, making it necessary to go all the way back to the blasting cabinet or tumbler.  You'll never trust that wire wheel again, either.
• Install your hanger wire(s) on each part right after the mechanical cleaning steps have been completed.  Better to make the hanger wire too long than too short.  Extra length lets you adjust on the fly so that the part sits at the right depth in the electrolyte bath.  For parts with complicated shapes or partly-'shaded' surfaces, install two hanger wires in different places so that you can quickly/easily change the part's orientation relative to the anode(s) when you're half-way thru the plating cycle.
• With all of this semi-religious cleaning, your parts are really vulnerable to flash rusting in between steps.  For that reason, keep them immersed in a distilled water bath between cleaning steps.  Don't let them sit in the water for very long, either.  Flash rust is your #2 enemy in electroplating.
• Consider heating of the electrolyte bath to be mandatory.  Keep it in the 100 - 110 degree F range.  I rigged up a hot-water-tank heating element to do this.  I heat the bath to 110 degrees before I start each 20-minute plating cycle and then I remove the heater.  The temp never drops under 100 degrees during the 20-minute plating cycle.  Clean the heating element with alcohol before you drop it into your $200 electrolyte bath.
• Consider a bubbler in the electrolyte bath to be mandatory (a cheap one from the Pet Supply store works fine).  Clean the plastic tube with alcohol before you drop it into your $200 electrolyte bath.
• Consider heating of the detergent bath to also be mandatory.  I bought a cheap crock pot.  It works fine. Put the crock pot liner with the detergent mixture in the microwave for about 10 minutes to get it up to temp.  The crock pot element will handle it from there.
• I haven't bothered with heating for the acid dip or for the chromate dips.  I'm not convinced it makes a difference (and Caswell doesn't recommend it for the chromates).
• Add a 1/2 tsp of the Caswell brightener to the electrolyte bath every time you put a new part, or group of parts, in for a new plating cycle.  The brightener really does make a difference.  Just don't over-do it.
• It might be just me, but I've had poor luck trying to do multiple parts in one plating cycle.  Might be ok for nuts and small bolts, but I don't recommend you try it on anything else.  This adds a lot of time to the overall process.  However, every screwed up part adds even more time to the process.  I figure it makes more sense to devote the extra time towards making the part come out right on the first plating attempt, rather than spending the same time re-doing the entire process on several parts just because you wanted to speed things up.  This electroplating process just punishes mistakes.
• If a part is hollow (e.g. the infamous Inspection Light housing), the surface area that you use to calculate your amps should be the sum of the external surface areas only.  If you add in the internal surface areas, your amps will be too high and you'll 'burn' the part.
• The surface area of the edges of stamped-metal parts need to be included in your area calculations.  Most of the Z's little parts are 1 to 3mm in plate thickness.  You'd be surprised how much the edges contribute to the total surface area of each part.
• The iridescent 'yellow-green' result can only be achieved if you pre-dip in blue chromate.
• The iridescent 'yellow-green' appearance doesn't really show up when you remove the part from the yellow chromate bath.  It seems to really start to 'pop' after you rinse the part with water and then apply heat with a hair dryer.  Maybe just my imagination, but that's what I saw happening.

I'm not sure whether you've purchased a controllable-current power supply or not.  If what you've got won't let you control current, you can easily rig up a daisy-chain of park/turn-signal bulbs.  You can patch into the daisy chain at various points until you get the current that you're after.  Not as quick and elegant as turning a control knob, but a lot cheaper.  BTW, Radio Shack-type potentiometers won't work.  Even modest levels of amps burn them up.

Hope this helps.  Looking forward to seeing pix of your results.