thanks for your additional input.
The question is what the reason is for the insufficient open time - it could be false setting or impact of a (highly?) modified MC. In case of the latter we usually would recommend to work with a lower modified MC or reduce MC content slightly and compensate loss of sag by adding Optibent.
· Do you know loading level of Optibent?
· Any idea which MC has been used?
· What happened with the water demand when Optibent was additionally added to the system. Any higher water demand required – if know, I wonder why the additional amount of Optibent to the existing formulation should reduce the sag vs the formulation just with MC?
· Are we talking about C1 or C2 tile adhesive?
Alternatively we may recommend Optibent 6042 and play with the amount of MC. Pleae note usually a higher water demand may help to improve open time as long as sag is ok – according to our experience Optibent allows a slightly higher water demand without harming sag which should result in improved open time (reduced skin formation.
If the open time is related to setting issues- possibly Optibent 1248 might be another option.
Sorry for so many recommendations but performance strongly depends on the formulation and type of binder used.