Eco-HTS 100. 100 Series colorants must be used if VOC of the mix needs to be <100 g/L. Standard colorants can also be used in Eco-HTS 100. It is important to have a consistent base coat in a similar color before application or multiple coats may be needed. Use colorants at the rate of 1 unit per gallon (3.78 litres) of Eco-HTS 100.