Type：

Sealing Salt

Model：

SMH

Property：

SMH is applicable to non-stain sealing of anodized film with 

excellent sealing quality. By addition of SMH to the sealing bath,

stainless sealed film can be obtained on transparent oxide film or

overall coloring, electrolysis coloring and organic adsorptive dyed film.

Working condition：

Usage amount mainly depends on water quality and the type of oxide film, preferably with deionized water. In order to ensure the best sealing condition, the pH value should be examined and adjusted with dilute ammonium hydroxide or acetic acid as required when preparing sealing bath solution or during its use process. As a stain inhibitor of sealing, the concentration of SMH should not be too high, otherwise, the weight loss of “weight-loss method after immersion in phosphochromic acid with nitric acid pre-dip” in sealing quality test will increase (ISO 3210).15 ml/L of high concentration is still acceptable.

Spectrophotometric Determination of SMH in Bath Solution:

Principle: The extinction value at 237 nm of a bath sample is

compared with an SMH solution of known

concentration.

Reagent: Use only distilled or deionized water to prepare the solution and mix with those thoroughly.

Solution A: Dissolve 2.0 g of ammonium acetate in water and fill up to 1000 ml in a measuring flask.

Standard solution: Place 4.0 g of SMH solution in a 1000 ml measuring flask and fill up with water to 1000 ml, then place 5 ml of this solution in a 100 ml measuring flask and fill up with solution A to 100 ml.

Sealing bath solution: Place 5 ml of the bath solution in a 100 ml measuring flask and fill up with Solution A to 100 ml.onizedith nitric acid pre-dip