Why was horse hair used in plaster?

Horsehair was used in plaster as a natural reinforcement material that increased the strength and durability of the plaster. The fine strands helped to prevent cracking during the drying process and improved the overall adhesion of the plaster to surfaces. Additionally, horsehair was readily available and cost-effective, making it a practical choice in construction during earlier periods. This traditional technique is still appreciated for its effectiveness in creating resilient plaster finishes.