Protection upgraded

SurTec® 650 RTU

chromitAL TCP - RTU
Ready-to-Use Solution

Properties
 free of hexavalent chromium
 trivalent chromium passivation for aluminium
 ready-to-use solution for spray and wipe application
 viscous adjusted solution for better and longer moistening
 excellent bare corrosion protection, comparable to hexavalent passivations
 very suitable as pre-treatment before lacquering, powder coating and gluing
 produces visible, faintly blue to tan iridescent layers
 meets or exceeds MIL-DTL-81706 and MIL 5541 for bare corrosion
(336 h in NSS per ASTM B-117, respectively, DIN 50021 SS)
 low contact resistance: < 5000 µOhm per square inch as per MIL-DTL-81706B
 heat resistant up to 100°C with minimal loss in corrosion resistance

Application
SurTec 650 RTU Ready-to-Use Solution is used undiluted for spray or wipe application.
Make-up-value: 100 %

Temperature: room temperature

pH-value: 3.8 (the ready-to-use solution is adjusted accordingly)

Application time: 2 min (1-10 min)

Spray pressure: 1 bar (0.5-1.5 bar)

Tank material: stainless steel, or steel with acid- and fluoride-resistant coating

Heating/cooling: not necessary

Exhaust: according to local requirements

Hints: During storage, a slight precipitation may occur, which does not impair the
quality and the function of the product.

Surfaces treated with SurTec 650 RTU can be coated immediately after
drying or stored as long as they are protected from contamination and
temperature extremes. For optimum results, the parts should be coated
within 7 days.

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Treatment Procedure
Pre-treatment: Prior to the passivation with SurTec 650 RTU, the aluminium surface must
be cleaned and deoxidized thoroughly. The surface must be completely
water-break free.

Cleaning can be done with:

 solvents or solvent-based cleaners (e.g. by rubbing the surface with a

soaked cloth); if applicable, the surface can be treated with Scotch
Brite or abrasive paper in order to remove corrosion products from the
surface; abrasion should be done under water cooling, the abrasive
dust must be removed by a wet cloth
 aqueous, acidic, phosphate-free cleaners (a subsequent rinsing is
required)
 a combination of alkaline cleaning and subsequent acidic desmutting
(between the two steps and after desmutting, the surface has to be
rinsed with water)

Treatment with SurTec 650 RTU chromitAL:

Wet the surface with the ready-to-use solution, e.g. by using a sponge,
brush, cloth or spray pistol.
Make sure that the surface is completely wettable with SurTec 650 RTU
solution (no contraction/coalescence of the liquid film and no dewetting
or formation of separate drops). In case of dewetting, repeat the pre-
treatment/cleaning steps.
During the required application time (typically 2-4 min), the surface must
be kept permanently wet with SurTec 650 RTU solution. There must not be
any drying on the surface. In order to avoid a surface drying use more
SurTec 650 RTU solution, if necessary.
A continuous, slight, mechanical treatment (wiping, brushing) supports the
uniform formation of the passive layer.

Post-treatment: After passivation in SurTec 650 RTU, the parts have to be rinsed. For best
corrosion resistance and best paint adhesion, a rinsing with deionised
water is recommended. For subsequent lacquering, the last rinse must
have a conductivity of less than 30 µS/cm.
The parts can be dried at environmental conditions, in case of forced
drying the drying temperature should not exceed 65°C at the part's
surface.

Technical Specification
(at 20°C) Appearance Density (g/ml) pH-value (conc.)

SurTec 650 RTU liquid, green, clear-turbid 1.003 (1.00-1.01) 2.9-4.0

contingency precipitate
Note: During the first days of storage, the pH-value of the product could slightly
increase.

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Maintenance and Analysis
SurTec 650 RTU as a ready-to-use solution is supplied in the required make-up concentration.
Therefore, an analysis is not necessary.

Ingredients
 trivalent chromium salts

Consumption and Stock Keeping

The consumption depends heavily on the drag-out. To determine the exact amounts of
drag-out, see SurTec Technical Letter 11.

In order to prevent delays in the production process, per 1,000 l bath the following amount
should be kept in stock:

SurTec 650 RTU 1000 kg

Product Safety and Ecology

Classification and designation are noted in the Material Safety Data Sheets (according to the
European legislation). The safety instructions and the instructions for environmental protection
have to be followed in order to avoid hazards for people and environment. Please pay attention
to the explicit details in our Material Safety Data Sheets.

Warranty
We are responsible for our products in the context of the valid legal regulations. The warranty
exclusively accesses for the delivered state of a product. Warranties and claims for damages
after further processing of our products do not exist. For details, please find our country-specific
General Terms and Conditions for downloading on our homepage or ask your regional SurTec
representative.

Further Information and Contact

If you have any questions concerning the process, please contact your local technical
department.

For further information and contact details, please visit our homepage:
http://www.SurTec.com

25 March 2021

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