Mara^® Pur PU.

Recommendation
The ink should be stirred homogeneously before printing and if necessary during production.

Mara^®Pur PU is a 2-component ink system. Prior to printing, it is essential to add hardener / adhesion modifier in the correct quantity and to stir homogeneously.
The proper mixing ratios are:

Basic Shades:
4 parts by weight ink : 1 pbw Hardener

Varnish 910/911:
3 parts by weight varnish: 1 pbw Hardener

For ink mixtures of basic shades with varnish PU 910, the proper addition of hardener must be calculated in the correct ratio.
When using hardener, the processing and curing temperature must not be lower than 15°C as irreversible damage can occur. Please also avoid high humidity for several hours after printing as the hardener is sensitive to humidity.

Pre-reaction time
It is recommended to allow the ink/ hardener mixture to pre-react for 15 minutes.

Pot life
The ink/hardener mixture is chemically reactive and must be processed within the mentioned time frame (referred to 20-25 °C and 45-60 % RH). Higher temperatures reduce the pot life. If the mentioned times are exceeded, the ink's adhesion and resistance may be reduced even if the ink still seems processable.

PU + H 1: 8 hours
PU + H 2: 4 hours

By continuously adding freshly mixed ink plus hardener, the pot life can be extended up to 24 hours (3 shifts).
With the use of HT 1, there is no pot life to consider since this hardener is only activated by a baking process (30 min/150° C).

Parallel to physical drying, i.e. evaporation of solvents, the actual hardening of the ink film is caused by the chemical cross-linking reaction between ink and hardener.
The following standard values concerning the progressive cross-linking reaction (hardening) of the ink film are experienced (fabric 100-40):

The mentioned times are only guidelines as the drying times above vary according to the prin-ted ink film thickness, air humidity, drying conditions and selection of auxiliaries used such as thinner and/or retarder.
If multicolour prints are dried with forced heat between printing sequences (by hot air or infrared), the time for overprinting is reduced to approx. 3-4 min. 
Due to the extreme stress for substrate and ink, we do not recommend intermediate drying by flame. When drying with forced heat at more than 160° C, the heat application must not exceed 5 min as otherwise, there will be a yellowing, especially with White 070. Generally, an extended drying time is necessary when over-printing the ink. Processing and hardening temperatures should not be below 15° C during printing and 8 hours after printing, otherwise irreversible damage can occur.
Please also avoid exposure of the ink to high humidity or water (rain) during and after printing for 8 hours at 20° C or 12 hours at 15° C, because adhesion between ink and substrate will be affected. 

Overprinting
Please pay attention to the fact that the ink film underneath is not chemically cured when first overprinted. If the ink film is dried at room temperature of 20° C, overprinting must be carried out with Hardener H 1 within 12 hours, resp. with Hardener H 2 within 8 hours at the latest. We recommend to carry out the overprinting as soon as possible in order to guarantee good adhesion of the ink layers.