How to Store Paint Correctly

Here is how to store paint for future projects:

1. Seal the Container Tightly: Close the lid of paint cans tightly after painting the substrate. Don’t leave it open, as air exposure affects the paint storage. It allows the VOC compounds to evaporate and cause serious health hazards. Air exposure also leads to paint hardening, fading, and contamination after the solvents vaporize. Seal the paint container to maintain its density and viscosity. 
2. Store in a Cool, Dry Place: Preserve the paint containers between 60°F and 80°F (15°C to 27°C) temperature to protect from molding. Store it in a cool and dry place with a 40 to 60% humidity range to protect from hydrolysis and structural damage. High temperature increases the movement of paint molecules and changes the paint viscosity. Low temperature with high moisture promotes mildew growth. 
3. Keep Away from Direct Sunlight: Store the paint containers in a location away from direct sunlight. UV radiation deteriorates the binding ability of resins and polymers to hold pigments together. Sunlight exposure changes the formulation of paint and leads to poor paint adhesion. It also fades the color and alters the paint texture to chalky (powdery). 
4. Label the Paint for Future Use: Label the paint lid or side of the container before storing it. Put the details of paint color, finish, and where it was used to identify it in the future.
5. Smaller Containers When Needed: Pour the paint into mini airtight containers and use one or two when needed. It prevents the large paint cans from air exposure when a small amount of paint is required for touch ups. Don’t throw away if a little paint is left behind after painting. Move them into these small cans to fill the paint cracks in the future. 
6. Use Plastic Wrap for Extra Protection: Can lids erode and lose over time due to rust. Make sure to wrap the paint containers in plastic wraps to prevent water exposure. Plastic is a non-biodegradable material and protects paint from all environmental factors except flame. Store the paint cans in a safe place away from heaters and thermostats. 
7. Keep the Exterior Clean and Rust-Free: Clean the paint cans thoroughly before storing them. Remove the solidified paint drips on the sides of the container with a slightly wet cloth. Leave it in sunlight or use microfiber to dry the tin completely. It prevents the rust-effects paints from contamination. Organize the paint cans upright to minimize the risk of leaks and messy shelves.

How Do You Check If Leftover Paint Has Expired?

Here is how to check if leftover paint has expired:

1. Strong sour: Paint releases a foul odour and a rotten smell when it expires. This bad odor occurs due to microbial growth inside the cans. These bacteria release ammonia and hydrogen sulfide as a byproduct, which smells like rotten eggs. 
2. Mold growth: Mold and mildew growth are visible signs of expired paints. Mold in cans occurs due to various factors such as mold spores, moisture, plasticizers, and biocides. Plasticizers are the preservatives in enamel and alkyd paints, which become the food source of mold. Water-based paints contain fewer preservatives to resist bacterial growth, and they form clumps that don’t mix.
3. Blendability: Expired paints have poor texture, consistency, and final finish. Pigments and binder separate and settle down in cans. Visible bubbles and watery consistency of paint don’t blend even after stirring for hours. 
4. Rubbery film on top:  A rubbery paint film forms on the top after it expires. It occurs due to changes in chemical bonds and binders. This rubbery texture is a fluff that lacks the resin content and does not change its viscosity. Do not use them on walls and furniture as they do not last long. 

What Are the Best Paint Storage Practices for Specific Users?

Here are the three practical tips for paint storage for specific users:

1. For DIYers & Homeowners: Use clean tins and mini jars to store paint at home. Don’t throw away the lids after opening the can. Use a mallet (soft rubber hammer) and cover the paint cans. Use a screwdriver and apply gentle force to open this lid when needed.
2. For Artists & Crafters: Read the manufacturer’s instructions and preserve the paints accordingly. Artists can store paints in machine drawers, shelves, racks, plastic bins, PVC pipelines, and rotational organizers. Sort the paints by color and divide them into categories for easy finding. 
3. For Contractors & Pros: Store the bulk paint in its original container and on a concrete floor to prevent rust. Control the temperature conditions and clean the warehouse thoroughly. Implement a tracking app to check the expiry, best before and stock details. 

How Long Does Paint Last in Storage?

Here is the complete detail of how long a paint lasts in storage:

1. Unopened latex or acrylic paint: Water-based paints such as acrylic or latex last up to ten years when stored under ideal conditions. Unopened chalk and milk paints are stored for one to three years, based on the external weather conditions. 
2. Opened the latex paint: Opened latex paint stays for two to five years when the can is properly sealed with a mallet and wrapped in plastic.
3. Spray paint: Spray paint that comes ready to use lasts for 2 to 3 years. Clean the nozzle after using it once with a dry microfiber. Block the air exposure and shake the can to prevent the pigments from setting. Spray paint expires if the nozzle gets clogged or the paint does not come off easily. 
4. Oil-based paint: Unlike water-based paints that expire quickly, oil-based paints last up to 10 years in both unopened and opened (airtight sealed) conditions. It is due to their different chemical composition, primary solvents, and drying process.