Using old opened paint is a common question for many DIYers and homeowners. Paint can be expensive, so it’s understandable why someone may want to use a half-used can that’s been sitting around for a while. However, there are a few factors to consider before using old paint. The main things to think about are:
- How long has the paint been opened?
- What type of paint is it (latex vs. oil-based)?
- Has the paint gone bad or dried out?
- What are you planning to paint?
- Will you need to thin or strain the paint before using it?
In this article, we’ll explore these key questions to help determine if you can use that old opened paint or if it’s best to purchase a fresh can. We’ll also provide tips on storing paint properly to get the longest life out of it.
How Long Has the Paint Been Opened?
The first thing to consider is how long ago you first opened and used the paint can. As a general rule of thumb:
- Latex paint lasts about 2 years once opened
- Oil-based paint lasts about 1 year
However, these timeframes assume you’ve stored the paint properly in an airtight container in a climate-controlled environment. Heat, cold, direct sunlight, or moisture can cause the paint to spoil or dry out faster.
If your paint is older than the recommended shelf life, it’s best to dispose of it and buy fresh paint. Old paint may still apply, but it will likely have some negative qualities like poor coverage, clumping, odor, and uneven sheen.
What Type of Paint is It?
The base of the paint matters when determining if it can still be used. Here’s a quick comparison:
- More forgiving of storage mistakes
- Can last 2+ years when stored properly
- Water-based so easier to thin and strain
- Dries out faster once opened compared to oil
- May grow bacteria and smell bad when expired
- Very durable and long-lasting
- Has up to a 1 year shelf life
- Less prone to spoilage than latex
- Difficult to work with once dried out
- Need chemical thinners to reconstitute
- Fumes linger when applying
In general, latex paint is easier to revive and use past its prime compared to oil. But neither will function optimally beyond their recommended shelf lives.
Has the Paint Gone Bad?
Even if your paint falls within the use-by timeframe, you’ll still want to inspect its condition thoroughly before applying it. Here are some signs your paint has expired:
- Thick texture: Paint should flow easily off a stir stick. Thick, gummy paint is past its prime.
- Separation: Pigment and carriers separate, leaving watery liquid at the top.
- Mold/algae growth: This appears as film or colored spots in the paint.
- Unpleasant smell: Rancid odors mean the binders and carriers have broken down.
- Color changes: Dramatic lightening or darkening signal chemical alterations.
Mild drying and skinning on the surface can often be remedied by straining and mixing thoroughly. But anything more serious usually means it’s best to discard the remainder and start fresh with new paint.
What Are You Painting?
Consider the surface you intend to paint before using old paint. Certain applications are more forgiving than others:
Best uses for old paint:
- Outdoor fences, decks, concrete, masonry
- Sheds, garages, workshops
- Basements, crawlspaces, attics
- Spare furniture, craft projects
Worst uses for old paint:
- High-traffic areas like hallways
- Kid’s rooms, dining rooms, living areas
- Kitchens and bathrooms
- Outdoor house trim and shutters
- Furniture and surfaces requiring fine finishing
It’s best to use fresh paint for any visible, high-traffic surfaces where you want a flawless painted finish. Areas where durability and aesthetics matter less can be safely painted with older paint.
Thinning and Straining Old Paint
If you determine the old paint is still usable, you may need to thin and strain it before applying:
- Use water to thin old latex paint – Start with 2 oz water per 1 quart paint
- Mineral spirits is best for thinning old oil-based paints
- Mix thoroughly and test consistency on cardboard
- Repeat adding small amounts of thinner until optimal consistency is reached
- Use a paint filter, cheesecloth, or fine mesh strainer
- Work in small batches to prevent spills and messes
- Stir paint in a circular motion as you pour it through the filter/strainer
- Catch any lumps or skins in the filter – they should not pass through
- Seal and remix strained paint before using
Proper thinning and straining can fix minor clumping and separation issues. But if the paint still doesn’t apply evenly, it’s best to dispose and replace.
How to Store Paint Correctly
To get the longest life from paint, proper storage is crucial:
- Wipe and clean rim of can before sealing lid tightly
- Cover surface with plastic wrap under lid to create air-tight seal
- Store cans upside down to keep lid immersed and prevent air exposure
- Maintain storage temperatures between 50-90°F
- Avoid direct sunlight which can heat and deteriorate paint
- Keep paint away from furnaces, fireplaces, and heat sources
- Don’t let paint freeze – store in temperature controlled area
Following these guidelines will add months or years to the usable life of your leftover paint. Buy only what you’ll use up quickly, or invest in smaller cans for paint colors you’ll need only a small amount of.
To summarize, here are some final tips on using old paint:
- Latex paint lasts 2 years, oil paint lasts 1 year once opened
- Inspect thoroughly for changes in texture, smell, and color
- Thin and strain paint that has mildly dried out or separated
- Use in low-visibility areas rather than high-traffic surfaces
- Discard paint that’s lumpy, rancid smelling, or severely deteriorated
- Store paint properly to maximize shelf life after opening
With proper care and storage, some paints may last many years past their expiration date. But for a seamless paint job with minimal frustration, it’s usually best to use fresh paint whenever possible. Planning ahead and buying only what you’ll use in the near future will save you money and prevent having to toss old paint that’s gone bad.