Plaster of Paris vs joint compound?

Plaster of Paris sets fast (20 min) and does not shrink, making it ideal for small repairs. Joint compound dries slowly and is used for full drywall finishing. They serve different purposes.

Can I use it to fill large holes?

For holes larger than 3-4 inches, use a drywall patch kit instead. Plaster of Paris is best for small repairs and patching.

No. Plaster of Paris dissolves when exposed to water. It is strictly an interior product.

Plaster of Paris

Drywall & Plaster

Plaster

$5-$15 per 4-8 lb container

Plaster of Paris: Quick-Setting Gypsum Plaster (2026)

Prepared by Lumberama's Building Materials Team

|Last updated May 15, 2026|Sources & methodology

Plaster of Paris is a fine white powder made from heated gypsum that, when mixed with water, forms a paste that hardens rapidly within 20-30 minutes. It is used for quick wall repairs, casting molds, ornamental work, and small patching jobs. Its fast set time makes it ideal for overhead and vertical repairs.

Key Features

Sets in 20-30 minutes; Smooth white finish; No shrinkage; Easy to mix; Good for overhead work

Specifications

Mix ratio: approximately 2 parts plaster to 1 part water. Set time: 20-30 minutes. Working time: 5-10 minutes. Compressive strength: 2000+ PSI when cured. Available in 4-25 lb bags.

Applications

Small wall repairs; Ornamental casting; Plaster mold making; Patching holes; Decorative moldings

Installation Overview

Sift plaster into water (never water into plaster) until it mounds slightly above the surface. Let it slake for 1-2 minutes, then mix to smooth consistency. Apply quickly as working time is short. Do not retemper once setting begins.

Pros & Cons

Pros

✓ Very fast set time; No shrinkage; Smooth finish; Easy to mix; Good for vertical and overhead work

Cons

✗ Very short working time; Cannot be retarded once mixed; Not weather resistant; Brittle when cured; Not for exterior use

Top Brands

DAP

USG

Quikrete

Code Requirements

No specific building code requirement. Used for repair and decorative purposes. Structural repairs should use appropriate drywall compound or patching plaster.

Buying Tips

Mix only what you can use in 5 minutes - it sets quickly. Cold water extends working time slightly. Keep mixing tools clean as set plaster is hard to remove. For larger repairs use a setting-type joint compound instead.