Foshan Dechenghezhong Chemistry co.,LTD
No,12 Yuyang 2nd Road, Huchong Industrial District, Nanzhuang Town,
Chancheng District, Foshan City, Guangdong, China
Tel:0086-757-82012410
Fax:0086-757-82012430
Website:http://dchz.en.alibaba.com
E-mail:fsdchz@outlook.com
DCHZ-Prep220 Brass Activator
DCHZ-Prep 220 brass activator salts are a dry, free-flowing powdered mixture which is dissolved in water
at a concentration of one (1) pound per gallon. The alkaline solution is used at a boiling temperature
of 220°F as a pre-dip prior to blackening brass surfaces with DCHZ-Cu420 to ensure the
formation of a uniform black oxide conversion finish on brass
(high zinc, 15% to 35%, alloyed copper surfaces).
SOLUTION MAKE-UP AND MAINTENANCE
Calculate the operating volume of the tank leaving 6 inches of free board. Determine the total
poundage of salts required using one (1) pound per gallon. Fill the tank half full with cold water. Do
not apply heat. A full ace shield, rubber gloves and rubber apron must be worn while mixing
the solution. Slowly add the salts to the water while thoroughly and continuously stirring the solution
to avoid the formation of lumps. The salts should be added (sprinkled) over the entire surface
of the water while stirring to avoid violent splattering on the surface. When the total amount of salts
have been added, the tank should be filled with water to within 6 inches of the top while stirring
continuously.Once the tank is filled, heat is applied and the solution is stirred to ensure a uniform
temperature throughout while the temperature rises to 220°F, at which time the solution should begin
to boil. If the solution boils before reaching 220°F, additional DCHZ-Prep 220 salts should
be added to raise the boiling point. If the solution does not boil at 220°F, then water should
be slowly added until the solution just begins to boil (simmer). The solution should be held at operating
temperatures below 220°F for at least one hour before adding additional salts to raise the boiling
point. This will ensure that all salts previously added have been completely dissolved and the
true boiling point has been reached.
The chemical strength of the solution is maintained by controlling the boiling point at 220°F by
adding water when too high and salts when too low. The boiling point will rise due to evaporation
of water and an electronic temperature controller should be used to automatically and safely
control the addition of water. To ensure consistent and uniform finishes, detrimental over-heating
must be avoided and frequent small additions of replenishment salts should be made rather than
large amounts added less frequently. The accuracy of the automatic temperature controller
should be checked frequently.The maximum load (including the weight of processing barrels,
baskets and racks), should not exceed two (2) pounds of work per one (1) gallon of solution
with one (1) pound per gallon being optimum. The temperature of the solution should not be allowed
to drop below the boiling point for more than a few minutes when work is introduced. Therefore,
the heating system for the tank must be designed to ensure that sufficient heat capacity is available
to handle the heaviest loads.
FINISHING PROCEDURE
Parts to be blackened may be processed in mild steel baskets, tumbling barrels or on mild steel
hooks or racks.
1. CLEAN: Parts must be thoroughly cleaned and degreased for 5 to 10 minutes in a hot(180°F)
solution of DCHZ-1002 alkaline soak cleaner at 8 wt. oz. per gallon of water.
2. RINSE:Using a bottom-fed, overflowing cold water rinse tank.
3. DEOXIDIZE: Immerse parts for 30 seconds to one (1) minute in a room temperature 25% to 50%
by volume Muriatic Acid solution or in a 8 oz. to 2 lb. per gallon solution of DCHZ-Pik 211 to
remove surface oxidation.
4. RINSE:Using a bottom-fed, overflowing cold water rinse tank.
5. ACTIVATE:Immerse parts for one (1) to three (3) minutes in boiling 220°F DCHZ-Prep 220 solution.
Required immersion times will vary from one (1) to three (3) minutes depending upon the mass of
parts and the type and condition of the metal surfaces.
6. BLACKEN: Immerse parts without an intervening rinse in DCHZ-Cu420 solution maintained at
210°F to 220°F until a uniform, deep black color is developed. Immersion times will vary from 5 to 20
minutes depending upon the amount of alloyed zinc.
7. RINSE:Using a bottom-fed, overflowing cold water rinse tank.
8. SEAL:The finish must be sealed and depth of black enhanced by immersion in a solution of
DCHZ-Tec 501 for an oily finish,or spray painting for a hard, dry, clear finish.
EQUIPMENT
The tanks to contain the DCHZ-Prep 220, DCHZ-Cu420, DCHZ-1002, DCHZ-Tec and rinse waters may
be constructed of stainless steel or mild steel. The acidic DCHZ-Pik 211 and Hydrochloric Acid
deoxidation/activation solutions must be contained in polypropylene or rubber lined steel tanks.
