Add Thompson's Mortar Plasticiser to a rate: 150ml- 500ml per 50kg of cement, depending upon degree of plasticising required, or 2.5 lire per 200 litre drum of water. (The coarser the sand the greater addition rate required).

What happens if you use too much plasticiser?

Excessive use of plasticisers can have an adverse effect on the mortar. Lime added to mortars is well known for giving them a soft, putty-like consistency which can make them easier to work and retard their setting.

Is plasticiser necessary in mortar?

Plasticisers are chemicals that are added to mortar mix to give a little more flexibility before setting, which is useful for noticing uneven patches and holes. Plasticiser also makes mortar set stronger, while making it more resistant to frost.