TECHNICAL DATA SHEET
SurTec 650V
Trivalent Chromium Conversion Coating - Visible
Description Trivalent Chromium (Hexavalent Chromium-free) conversion coating for aluminium, which
produces a visible blue-grey to yellow iridescent layer.
Features • Excellent corrosion protection.
• REACH, RoHS and WEEE compliant.
• Designed for immersion application but can also be spray or wipe applied.
• Can be used to repair anodised coatings and refresh them before painting.
• Approved for aerospace use to MIL-DTL-81706 and MIL-DTL-5541F. Also approved
by Qualicoat for architectural aluminium.
• Supplied as a concentrated liquid.
• Low electrical resistance.
• Drop-in replacement for hexavalent chrome passivation.
Product Code MP0252.
SG 1.00 + 0.1 kg/l at 20oC.
Equipment The SurTec 650V tank and water rinse tanks can be made of polypropylene
(recommended), rigid PVC or stainless steel.
Initial Fill SurTec 650V must be made up with deionized or demineralized water at concentrations
from 5% to 30% by volume (see Control Points). Before make up, the tank must be
thoroughly cleaned and rinsed.
Application The process sequence is usually:
1. Aqueous degreasing with T Cleaner 70 (MP0035) non-etching - dip for 3 - 15 min at
60°-70°C.
2. Water rinse.
3. Alukleen (acidic) or T Cleaner 79 (alkali). Dip 30 seconds to 10 min at ambient
temperature.
4. Deionised (Demineralised) Water Rinse.
5. SurTec 650V Dip for 1 – 4 min at 30o – 40oC.
6. Deionised (Demineralised) Water Rinse – normally 2 stages, see RINSING below.
7. Dry off (at maximum 60oC).
The addition of a nitric acid rinse before the SurTec 650V step can improve performance.
Further treatment should be applied no longer than 16 - 24 hours after SurTec 650V
application.
Control Points For Bare Metal:
Concentration 18 - 25%
Acidity (pH) 3.7 - 3.9
Temperature 30o - 40oC
Time 1 - 5 min.
www.trimite.com Page 1 of 2
TECHNICAL DATA SHEET
SurTec 650V
Trivalent Chromium Conversion Coating - Visible
Analytic Control Titration:
Accurately measure 100 ml sample of the bath into a conical flask. Acidify with 10 ml of
40% sulphuric acid. Add 3 g of ammonium persulphate. Boil for 20 minutes.
Cool to room temperature. Add 1 g of potassium iodide and 10 ml of 40% sulphuric
acid. Leave for 1 minute until dissolved. Add 0.5 g of iodine indicator.
Titrate slowly against 0.1 M sodium thiosulphate. Titrate until colour changes to
clear/light blue.
Each ml required x 1.613 = concentration %.
A Test Kit (MP0614) is available from Trimite containing all the necessary items.
Replenishment:
Add 10 litres of SurTec 650V per 1000 litres of bath for each 1% by which the bath is
short.
Acidity:
Measure the pH of the bath with a reliable meter after replenishing with SurTec 650V. If
the pH is not within specification very carefully add 200 ml of 5% sulphuric acid or 1%
sodium hydroxide solution to each 1000 litres of bath as appropriate and re-check.
Add in further 100 ml increments if necessary. pH meters are available from Trimite.
Rinsing Rinse the work thoroughly in deionised or distilled water. The rinse bath should be
regularly maintained. A second, hot (50° - 70°C) rinse can be used to improve the rinsing
standard and assist in drying the work. This rinse should be changed regularly.
Drying For most reliable results, the work should be dried in an indirect-fired oven at
60°C maximum.
Tank Maintenance Based on usage, the tank should be regularly emptied, cleaned, and refilled.
Shelf Life For best before date, see label.
Storage The product should be stored in cool, dry, frost-free conditions, in sealed containers.
Health & Safety Refer to the product’s Safety Data Sheet and safety advice on the product label
before use.
Technical Support For technical support in using this product, please contact:
e: birminghamtech@trimite.com, or
t: 0121 554 7000.
Date of Issue Sep 2022.
Information provided in this leaflet is given in good faith but without warranty or assumed liability, as the conditions of application and use are
beyond our control. Data are accurate to the best of our knowledge at the time of issue but may be revised in the light of new knowledge and
the user should check that data are current before use. The user must satisfy themselves about the product’s suitability for their own purpose
and refer to the Safety Data Sheet for this product before use. For industrial use only unless specifically stated otherwise.
www.trimite.com Page 2 of 2
