1. Process Instruction
Gardobond® A4940
Amorphous iron phosphate pre-treatment
Scope
Gardobond A4940 is a liquid amorphous iron phosphate solution designed to pre-treat
metal ferrous substrates, aluminium and zinc materials.
With suitable Gardobond-Additives, Gardobond A4940 can be used for simultaneously
degrease and pre-treat of metal ferrous substrates, aluminium and zinc materials.
Gardobond A4940 is applied by spray or by immersion.
Physical properties
Appearance: colourless – light yellow liquid
Density (20ºC): approx.1.3 g/cm³
pH value (60 g/l, 20ºC): 3,8
Flash point (DIN 51755 / 53213): non-flammable
Process sequence
Combined cleaning and degreasing
Cleaning / phosphating – rinsing – demin rinsing / post rinsing – drying and painting.
Separate cleaning and degreasing
Cleaning – rinsing – Phosphating – rinsing – demin rinsing / post rinsing – drying and
painting.
CHEMETALL GMBH Trakehner Straße 3 ® registered trademark
D-60487 Frankfurt a. M. The above data have been compiled to the best of our knowledge on the basis of thorough tests and
P. O. Box 90 01 70 with regard to the current state of our long practical experience. No liabilities or guarantee deriving
Surface Treatment D-60441 Frankfurt a. M. from or in connection with this leaflet can be imputed to us. - Reproduction, in whole or in part, only
Phone: +49 (69) 7165-0 with our express permission.
Fax: +49 (69) 7165-3018
Internet: http://www.chemetall.com

2. Gardobond A4940
Chemicals required
Gardobond A4940 (make-up and replenishment solution)
Gardobond-Additive H7143 (to reduce pH), either
Gardobond-Additive H7141 (to increase pH)
Bath make-up
Add per 1000 litres of working solution:
Spray: 10 – 30 kg of Gardobond A4940.
Immersion: 30 – 60 kg of Gardobond A4940.
Mix and heat to operating temperature.
This may be varied dependant on the degree and type of soiling to be removed.
Bath operation
Treatment time: Spray: 1 - 3 minutes
Immersion: 3 - 10 minutes
Spray pressure: 1 - 2 bar
Bath temperature: 45 - 65 °C
Bath concentration: 1.0 - 6.0 % Gardobond A4940
pH value: 4 – 5,5
These operating limits are for guidance only. Plant conditions will vary and your Chemetall
Field Support Engineer may recommend operation close to or even outside the limits
quoted under certain circumstances.
Bath control
Testing chemicals required
Indicator Solution 2 (phenolphthalein)
Testing Solution 1 (0.1N sodium hydroxide)
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3. Gardobond A4940
Total acid pointage
Take a 10 ml sample of the working solution, dilute with approx. 50 ml of distilled water
add 15 drops of Indicator Solution 2 and titrate with Testing Solution 1 until the colour
changes from colourless to pink. The number of mls of Testing Solution 1 required is
known as the Total Acid Pointage of the solution.
Gardobond A4940 is normally used in the range 3,5 to 20 points, depending on
application.
Bath replenishment
An addition of 2,8 kg of Gardobond A4940 per 1000 litres of working solution will raise the
Total Acid Pointage by one.
Pre-treatment
Separate cleaning and degreasing
Alkali cleaners are well suited for cleaning and degreasing.
Alkali cleaners are supplied by Chemetall under the designation Gardoclean®.
Cleaning additives
If Gardobond A4940 is used for combined cleaning and degreasing (see Process
sequence) in a single step, a Gardobond-Additive surfactant additive should be added.
This additive is used to increase the cleaning and degreasing performance of the process.
The Chemetall Field Support Engineer can recommend the precise conditions for any
given installation.
Equipment
Tank, spray tunnel, heating elements, pump main, spray tubes and
spray nozzles
General-purpose constructional steels to DIN EN 10025, with acid-resistant rubber lining
Chromium nickel steel, material no. 1.4541 (limited suitability)
Chromium nickel molybdenum steel, material no. 1.4571
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4. Gardobond A4940
Safety and handling guidance
Before using the product it is important that this complete document, together with any
relevant safety data sheet(s), have been read and understood. The safety data sheet(s)
will advise on all precautions, safety equipment and procedures necessary in the safe use
and disposal of the product.
Environmental guidance
All local and national regulations on the transport, storage, use and waste treatment of
chemicals in concentrated or diluted form, or as working solutions, plus any by-products
and contamination occurring as part of the process, must be obeyed.
All waste waters must be treated in accordance with national legislation and local
regulations prior to discharge to the sewer.
07/07-3
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