Plating Resources, Inc. announces the development of a revolutionary safe, and new way to add sulfate to hexavalent chrome plating baths.
This can be used for both hard and decorative plating, either when making up a new solution or when raising the sulfate level in an existing bath. Traditionally the sulfate has been increased using hazardous concentrated sulfuric acid.
Sulfuric acid is extremely dangerous to store and handle. Besides causing severe burns, it’s also very exothermic and is a strong oxidizer. This means it can boil back and literally explode back onto the operator’s face when added to a water-based solution, especially a hot one like a chrome bath.
Buffered Sulfate Adjuster is a dry powder that is s non-hazardous to ship and store; it’s rated for usage as only 1-health. And it doesn’t give off excess heat like exothermic sulfuric acid does, which means it can be safely added to a chrome bath, even a hot one.
Buffered Sulfate Adjuster also includes a buffer that improves the plating by smoothing the chrome deposit and helping overcome the effects of increased trivalent and heavy metal impurities.
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Background
The sulfate ion (SO4) is a true catalyst used in hexavalent chrome baths for hard and decorative chrome plating. Without sulfate, chromium wouldn’t be deposited. The amount of sulfate needed is dependent on the desired ratio (chromic acid: sulfate), which is determined by the bath type being used. The sulfate ratio should be closely controlled within +/- 5% maximum variance for best operation.
Concentrated sulfuric acid has been the source of sulfate ions for over 100 years. However, sulfuric acid is extremely hazardous to handle and store. It can cause severe burns and start fires from its oxidative nature, and it releases considerable heat (exothermic) when added to a water-based solution like a plating bath. A sulfuric acid addition must be made with extreme caution and care due to its exothermic nature, especially in a hot bath, because the acid can literally blow back into the operator’s face unless added very slowly and spread across the bath’s surface while using heavy agitation.
Buffered Sulfate Adjuster
Plating Resources, Inc. recognized this problem and developed a dry sulfate additive that doesn’t have these problems. This additive is compounded with a buffer that helps stabilize the bath to improve the chrome deposit. Unlike sulfuric acid, Buffered Sulfate Adjuster is relatively safe to handle and store. It’s rated 1-health, 0-flammability, and 0-physical hazard.
Its major benefits include:
- It’s easier to measure accurately, which avoids excess sulfate.
- It’s significantly less hazardous, being only slightly alkaline.
- It’s a dry powder, so it’s safer to handle and store.
- It’s not exothermic, which eliminates dangerous acid blow-back.
- It adds an additional buffer to the bath that improves plating.
Additions
The amount of Buffered Sulfate Adjuster needed for the bath is:
Buffered Sulfate Adjuster: (oz./gal. increase) x (bath gallons) x 0.11075 = Pounds to add.
Do not guess the amount needed; weigh it out using a small scale. Example: A sulfate increase of 0.25 in a 750-gallon bath would require 20.76 pounds; the decimal points can be converted to ounces by multiplying by 16; the example would then equate to 20 pounds and 12.2 ounces)
See New Bath Make-up below about only adding 90% of this amount when making-up fresh plating solution. Additions to existing baths should use 100% of the amount calculated above. There’s no need to make additions in several steps if the Buffered Sulfate Adjuster is measured accurately.
New Bath Make-Up:
We suggest adding only 90% of this initially. Then agitate the bath until it's fully dissolved and the bath is uniform, typically for one hour. Then do a sulfate analysis and add the balance needed based on this analysis. This avoids overshooting the desired level due to sulfate impurities in the water supply and the chromic acid used.
Caution
Although there is no particular danger involved with handling Buffered Sulfate Adjuster, it is a slightly alkaline industrial product and should be treated as such. However, this product is used in a hexavalent chrome bath which is considered hazardous. Avoid breathing any dust, and do not use without adequate personal protection equipment. This product must be handled in accordance with the directives provided in its SDS form. Flush with water in case of contact with skin. For eyes, flush with water for 15 minutes (do not rub!) and obtain medical attention. Read and understand the various SDS for chrome plating baths prior to handling or using this product.
