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Thanks Greg,
I remember reading about the embrittlement / heat/ 10.9 + hardness.
I will pull all of those out of this lot and already have new high torque and bolts for cams, flywheel, crank,etc.
Glad you pointed out the camshaft triangles..I will just find a coating that doesn't require anything invasive.
Worf,
Talked with plater yesterday to again align expectations.
Did you have any issues with getting the rails done also?
Regulators and Dampeners will not be plated.
There seems to be misuse of terms in this thread and unfamiliarity with how zinc plating works; and more importantly, how parts get that cool yellow-gold iridescent appearance. So maybe this will help...
Once the zinc is applied to the part (cathode / anode in a bath) the cool looking yellowness comes from a ~20-second bath in a dichromate solution. How well the part shines is up to the purity of the zinc and bath solution and how well the part was prepped. Brighteners can be added to the bath to increase the shine. The lightness or darkness of the yellow depends on how long the part sits in the dichromate solution. If you want a darker yellow/orange, let it sit in the solution an extra 10 seconds.
The REAL question I would ask a plater is how long is their plating process; or said another way, how thick is their zinc coating. If they're just doing a quick flash, I wouldn't waste my time as it will be "sacrificed" and gone in a year or two. If you want longevity, the thicker the better.
If you want to give new nuts/bolts or even new Porsche parts that don't have that cool yellow color (but are plated): in a clean plastic bucket add 1 gallon of distilled water (not tap water) and then add 35ml of battery acid (from any car parts store) to the distilled water. SAFETY NOTE: always add acid to water--NEVER add water to acid. As this is acid, ALWAYS wear nitrile gloves and safety glasses. Then add 365g of sodium dichromate (buy it on e-bay). Mix it together, put your parts on a copper wire and dip it in for ~20 seconds and then rinse with tap water.
I am familiar with the after-zinc bath to get correct coloring. The vendor I am using had mentioned the time needed for the coating thickness and my desires.
I had ordered the Sodium Dichromate for a color change to newer clamps. expect it to be in this week..
I appreciate the video Link. I forgot to save that one.
Eastwood also has a pretty good tutorial about the coloring process after plating.
Anyone have any recommendations on how to clean/degrease/brighten/protectyellow chromate without removing or fading the yellow chromate?
a dirt still remains. Degreaser and a tooth brush gets it here
I can tell you what not to let near it - Smple Green - it is the best degreaser and cleaner, but it will take that finish right off in a heart beat. I'd use mild dishwasher soap, warm water and a toothbrush, and just gently scrub it until clean.
A note on the health effects of messing with cadmium and zinc:
1. Cadmium: Cadmium is one of the most toxic elements that human beings can be exposed to at work or in the environment and has no known physiological role in mammals. Human exposure to Cd can occur through food, water, and the inhalation of cigarettes. Once absorbed, Cd is efficiently retained in the human body, where it accumulates throughout life with a half-life of 25–30 years. Recent studies indicate that cadmium is capable of inducing epigenetic changes in mammalian cells. Since aberrant epigenetics play a decisive role in the development of various cancers and chronic diseases, Cd may cause pathogenic risks via epigenetic mechanisms. Several epidemiological and experimental data indicate that chronic exposure to cadmium in human beings can be associated with carcinogenesis, primarily in the lung, but also in the prostate, kidneys, breast, urinary bladder, nasopharynx, pancreas, and hematopoietic system. Once absorbed in the liver and kidneys, cadmium induces the synthesis of metallothioneins, which are small metal-binding proteins that are very rich in cysteines. The major physiological functions of metallothioneins include the homeostasis of essential metal Zn and Cu, protection against the cytotoxicity of Cd and other toxic metals, and scavenging free oxygen radicals generated in oxidative stress. Cd++ ions are unable to generate free radicals directly; however, after cadmium exposure, there is an increased production of ROS, resulting in oxidative damage to various molecules, such as nucleic acid, enzymes, and membrane phospholipids. Additionally, Cd induces an increase in ROS formation, which in turn induces DNA damage and interaction with DNA repair mechanisms. Cd exerts its toxic effect mainly by blocking the mitochondrial electron-transfer chain by impairing electron flow through complex III (cytochrome bc1 complex). Excessive ROS production can lead to macromolecule oxidation, mitochondrial membrane depolarization, mtDNA mutation, and apoptosis. Furthermore, by lowering the potential of mitochondrial membranes, Cd disrupts the oxidative phosphorylation and decreases the synthesis of ATP. Cd induces oxidative stress and ROS, which are normally balanced by enzymatic (SOD, CAT, GPx) and non-enzymatic (GSH, vitamin C, vitamin E) antioxidant barriers.
2. Zinc:
Compared to several other metal ions with similar chemical properties, zinc is relatively harmless. Only exposure to high doses has toxic effects, making acute zinc intoxication a rare event. In addition to acute intoxication, long-term, high-dose zinc supplementation interferes with the uptake of copper. Hence, many of its toxic effects are in fact due to copper deficiency. While systemic homeostasis and efficient regulatory mechanisms on the cellular level generally prevent the uptake of cytotoxic doses of exogenous zinc, endogenous zinc plays a significant role in cytotoxic events in single cells. Here, zinc influences apoptosis by acting on several molecular regulators of programmed cell death, including caspases and proteins from the Bcl and Bax families. One organ where zinc is prominently involved in cell death is the brain, and cytotoxicity in consequence of ischemia or trauma involves the accumulation of free zinc. Rather than being a toxic metal ion, zinc is an essential trace element. Whereas intoxication by excessive exposure is rare, zinc deficiency is widespread and has a detrimental impact on growth, neuronal development, and immunity, and in severe cases its consequences are lethal. Zinc deficiency caused by malnutrition and foods with low bioavailability, aging, certain diseases, or deregulated homeostasis is a far more common risk to human health than intoxication.
Note on Zinc: It is an essential component of our resistance to viral infections. As a +2 charged ion it has a tough time crossing the cellular membrane. Therefore a zinc ionophore is needed to get it into the cell. Once in the cell it has a strong tendency to bind itself at the second bonding site on the DNA of viruses which in turn stops the virus from replicating itself. This is why you find zinc in throat lozenges and some cold and flu medicines.
So in conclusion: Cadmium is bad for you (really baaaaad) and zinc is good - in low doses...
Industrial Plating. Lafayette, Indiana. Charging $150 for cleaning and yellow zinc per batch. Don’t waste your time trying to do yourself!
Fantastic result, this is one great option!
I'm sure there are many more platers out there to use. One thing that is for sure, hand preparation is the recipe for accumulation in your body and many forms of this toxins damage can result.
As an example:"Psychiatric disorders are associated with long-term disability and huge social and economic costs. The possible influence of heavy metals exposure on public health remains a matter of concern. A recurring research question that persisted among researchers in neuropsychiatry has been “are psychiatric patients more likely to have a high body burden of lead or other heavy metals?” This is an update account on the role of lead and cadmium in psychiatry. This review, which has employed search words like “lead and cadmium in psychiatry”, “lead and cadmium in schizophrenia”, “lead and cadmium in psychosis” in citation indices such as PubMed, Google Scholar, Scirus, and Scopus. A total of 415 articles were found; 60 fulfiled the inclusion criteria. Evidence-based information suggests that lead and cadmium may be involved in psychiatry."
So, there are very few places left that do Cadmium plating due to the toxicity.
Quality Plating in Salt lake does it still. This stuff is amazing. I hade it done in the no color. It looks matte silver and looks really good. I don't ever have to worry about any of the bolts rusting or getting "stuck"
The problem with Zinc plating, chromated or not, is that it will ‘go away’ within 5-ish years unless it lives mostly in a dry climate-controlled environment.
Cadmium plating will last for decades provided you don’t put tooling marks into it; it’s a ‘soft’ plate.
Don’t aerosolize it. Don’t lick it. Don’t rub it under your armpits. Don’t handle it with bare hands (for safety and because the oils/acids on your hands will start its deterioration.)
The original plating on 928s was not Cadmium. It was zinc but the process used - resulting in near-cadmium longevity with zinc’s resistance to tool marks - is lost institutional knowledge.
04-01-2020, 09:12 AM
