Oil based paint, also known as alkyd paint, has been used for many years to provide a high quality, durable finish for both interior and exterior applications. Proper storage is important to maintain the quality and properties of the paint. Oil based paint can be prone to skinning, thickening, and even spoilage if not stored correctly. Here are some tips on how to best store oil based paint.
Quick tips for storing oil based paint
– Store at room temperature around 68-72°F. Avoid temperature extremes.
– Keep cans tightly sealed when not in use.
– Store paint upside down to create an airtight seal.
– For partly used cans, pour a thin layer of water or mineral spirits on top to prevent drying out.
– Don’t store paint in direct sunlight or near heat sources.
– Only store as much paint as you will use within 2 years. The shelf life is around 2-5 years for unopened cans.
– Write the date opened on the can so you know if it is still within usable shelf life.
Ideal storage temperature
The ideal storage temperature for oil based paint is room temperature, around 68-72°F (20-22°C). Temperatures should not fluctuate widely above or below this, as it can affect the paint properties. Very high temperatures can cause the paint to skin over or even gel. Freezing temperatures can permanently alter the paint chemistry and cause thickening or spoilage.
Garages, garden sheds, and other uninsulated structures often experience temperature swings beyond the ideal range. Try to store paint in basements, closets, and cabinets within your home to keep temperatures more regulated. If storing paint in a shed or garage is unavoidable, consider putting it in an insulated cooler or bin.
Keep the lid tightly sealed
It is crucial to keep the lid of the paint can securely closed when not in use. This prevents air getting in and maintains the proper viscosity of the paint. If air infiltrates the can, it can cause the paint to thicken and dry out.
Always wipe the rim and threads of the paint can clean before closing the lid. Leftover paint residue can prevent the lid from forming an airtight seal. Turn the lid until you feel it come to a firm stop point. Avoid over-tightening the lid as this can damage the seal.
Store upside down
Storing oil based paint upside down is recommended to create an airtight seal through the plug of paint already in the rim. This prevents air pockets from forming as the paint level goes down, minimizing the chance of drying out. The paint plug acts as a built-in preservation seal when the can is inverted.
Be sure to turn the can over gently to avoid mixing air bubbles into the paint. Air bubbles can also contribute to oxidation and spoilage over time.
Seal partly used cans
For cans that have already been opened and partly used, take measures to prevent drying out between uses. The most effective method is to pour a thin 1/4 inch layer of water or mineral spirits over the surface of the remaining paint. This liquid seal prevents air from contacting the paint.
Before using the paint again, simply pour off the water or mineral spirits and stir. The paint underneath should still flow freely. If not, try mixing in a small amount of mineral spirits to get it back to the proper consistency.
| Sealant | Notes |
|---|---|
| Water | Most common choice, readily available. May need straining if water causes clumps. |
| Mineral spirits | Excellent seal, won’t affect paint chemistry. Higher cost than water. |
Avoid direct sunlight
Light can degrade and fade paint over time. Store paint in cabinets, closets, basements or other places without windows and direct light exposure. At the very least, do not leave paint cans in direct sunlight for extended periods. If storing in a shed or garage with windows, cover the paint with a dark tarp or blanket.
UV radiation from sunlight can especially damage paint. Florescent lights can also emit small amounts of UV rays, so avoid overhead lighting shining directly on stored paint.
Maintain moderate humidity
The ideal relative humidity for stored paint is around 50%. Very high or very low humidity can affect paint viscosity and drying time. If humidity goes over 70%, oil based paint is prone to thickening and moisture condensation inside the can. Below 40% humidity can accelerate drying in partly used cans.
Unless you live in an extreme climate, the ambient humidity in most homes and garages will be in the 40-60% range suitable for paint storage. Using air conditioning or dehumidifiers helps regulate humidity.
Avoid heat sources
Areas that experience wide temperature fluctuations are not suitable for paint storage. This includes attics, sheds, and garages. Hot water heaters, furnaces, stove pipes, and other heat sources can radiate heat and deteriorate stored paint. Try to keep cans at least 3 feet away from any heat sources. Uninsulated walls also allow exterior temperature swings to influence interior spaces. An interior closet is often the best place to store oil paint.
Store paint off concrete floors
Set paint cans on shelving, racks, or wooden pallets up off cold concrete garage floors and basement slabs. The temperature difference between concrete and room air can cause condensation on the bottom of the can. It also allows unstable temperature fluctuations from the floor surface. Paint should optimally be stored at the room’s ambient air temperature.
Limit quantity stored
Only store as much oil based paint as you anticipate using within the product’s shelf life, which is around 2-5 years unopened. Storage conditions greatly impact shelf life, with heat and cold reducing longevity. Fresh paint also ensures the highest quality results.
Write the date you purchased pre-mixed paint on the can. For paint you have custom mixed, write the store mixing date on the label. This allows you to keep track of age based on when first opened.
Watch for signs of spoilage
Check stored paint occasionally for signs of aging. As paint slowly cures in the can, you may notice:
– Skin or film on surface
– Increased thickness and viscosity
– Phase separation with oil on top
– Mold or bacterial growth
– Strong rancid odor
If paint shows any of these warning signs, it is past its usable life and should be disposed of properly, not used.
Proper disposal
Oil based paint is considered hazardous waste and requires special disposal methods. Do not pour down drains, storm sewers or directly into ground soil. Check municipality guidelines for disposal instructions. Waste management facilities often have special drop off days for paint and other hazardous household waste. Allow unused paint to dry fully in the can before disposal.
Different oil paint types
There are different formulations of oil based paints:
Alkyd paint
Alkyd paint is the most common oil based paint today made from alkyd resins. It provides excellent adhesion, gloss potential, and durability. Suitable for both metal and wood surfaces in residential, commercial, and industrial applications. Dries to touch in 6-24 hours and fully cures in 3-7 days.
Linseed oil paint
Contains high levels of linseed oil derived from flax seeds as the binder. Provides a soft satin sheen and excellent color retention. Primarily used for exterior wood surfaces. Long drying time of up to 4 weeks until fully cured.
Tung oil paint
Features tung oil from tung trees as the curing oil. Tung oil offers superior UV resistance compared to linseed oil. Provides a hard, durable, glossy finish. Used for exterior metals and wood. Drying time around 7 days.
Enamel paint
Has an alkyd resin base with a higher gloss finish. May contain small amounts of varnish. Excellent hardness and scratch resistance. Used for wood trim, cabinets, machinery. Dries to touch in 8-24 hours.
Age and quality
The main enemy of stored oil paint is air. When volatile compounds in the paint oxidize after exposure to oxygen, it causes the paint to thicken and skin over. Paint that has exceeded its usable shelf life will not flow or spread properly during application.
Higher quality oil paints have additives called antioxidants that help slow the drying process in the can. This extends the shelf life significantly compared to cheap paints lacking preservatives. High volumes of oil also increase stability and shelf life.
Proper mixing and dilution
Before using paint that has been sitting in storage for a while, check that it stirs back to a smooth, uniform consistency. Use a paddle mixing tool to reach the bottom of the can. If the paint seems too thick, gradually add a small amount of mineral spirits as needed to thin it out.
Adding mineral spirits helps dissolve any dried oils on the surface and brings the paint back to its original viscosity. Take care not to over-thin the paint, which will reduce hiding power and longevity.
Summary of oil paint storage tips
– Room temperature around 68-72°F
– Airtight sealed lids
– Store upside down
– Use water or mineral spirits to seal opened cans
– Avoid direct sunlight
– Moderate humidity around 50%
– Keep away from heat sources
– Elevate off concrete floors
– Only store 2 years’ worth
– Check frequently for signs of aging
– Properly dispose of spoiled paint
Following these guidelines provides the best environment for minimizing changes to oil based paint while in storage. With the proper storage conditions, quality oil paint can last many years while maintaining its application and performance characteristics.
Conclusion
Oil based paint can undergo changes like skinning, thickening, and spoilage when stored improperly over time. Exposure to air, heat, cold, and light are the primary culprits that degrade oil paint in storage. Follow the tips outlined here regarding ideal temperature, humidity, light exclusion, quantity, and proper sealing. Storing paint in a consistent environment designed to minimize these factors will help keep it fresh and usable for the longest possible shelf life. With careful storage, an unopened can of high quality oil based paint can last up to 5 years while maintaining optimal quality and performance.
