Wooden clothespins generally hold up better outdoors than plastic ones if you choose a hardwood like cedar or beech and accept that they will eventually rot; plastic clothespins resist moisture and mildew but degrade from UV sunlight, becoming brittle and snapping within a season or two. The real answer depends on your climate, how often you leave them on the line, and whether you prioritize longevity or low maintenance.
Formula
This calculator gives a rough estimate of how many months a clothespin will remain functional outdoors before it breaks, rots, or becomes too brittle to use. The formula is:
Life = Months outdoors × (0.9 − 0.05 × (Sun hours / 24)) × Material factor
- Months outdoors – how long you plan to leave the pins on the line or store them outside (months).
- Sun hours per day – average direct sunlight the pins receive (hours).
- Material factor – cedar = 1.0, pine = 0.7, UV-stabilized plastic = 0.5, non-stabilized plastic = 0.3.
The sun term reduces life by up to 0.05 × (sun/24) per month, so full sun (24 h) cuts the base life by 5% each month. This is a general model, not a lab-tested prediction.
Worked Example
Using the defaults: 12 months outdoors, 6 hours of sun per day, and cedar wood (factor 1.0).
- Sun factor = 0.05 × (6 / 24) = 0.0125
- Base reduction = 0.9 − 0.0125 = 0.8875
- Life = 12 × 0.8875 × 1.0 = 10.65 months
So a cedar pin left out for a year in partial sun is estimated to last about 11 months. In practice, cedar pins can last 2–3 years if you bring them in after each use, but this model assumes continuous outdoor exposure.
Why Wooden Pins Last Longer in Some Climates
Hardwood clothespins—especially those made from cedar, beech, or birch—have natural resistance to moisture and decay. Cedar contains natural oils that repel water and insects, which is why it is used for outdoor furniture and siding. Beech is dense and resists splitting, though it needs a weatherproof finish to avoid water damage. In dry climates, a well-made wooden pin can last for years, with the spring eventually wearing out before the wood does.
Plastic pins, on the other hand, are typically made from polypropylene or nylon. These materials do not rot, but they are vulnerable to ultraviolet (UV) radiation. UV rays break down the polymer chains, making the plastic brittle. After a few months of strong sun, a plastic pin may snap when you squeeze it. Some manufacturers add UV stabilizers, but these only delay the degradation, not prevent it.
How Plastic Pins Fail Differently
Plastic clothespins fail in two main ways: the spring rusts or the plastic cracks. The spring is usually steel, and even in plastic pins, the spring is exposed. Once the spring rusts, it loses tension, and the pin no longer grips. The plastic body may also become chalky and weak. In cold weather, plastic becomes more brittle, so a pin that survives summer may shatter in winter.
Wooden pins fail by splitting, rotting, or losing the spring. The wood can swell when wet, making the pin hard to open. If the wood is not treated, it can rot at the point where it contacts the line, especially if the line holds moisture. However, wood is less likely to break suddenly; it gives warning signs like cracking or softening.
How to Choose for Your Outdoor Use
Consider these factors when deciding:
- Climate: Humid, rainy areas favor plastic (if you can shade them) or treated wood. Dry, sunny areas favor wood.
- Sun exposure: If your line is in full sun all day, wood lasts longer than non-stabilized plastic.
- Frequency of use: If you use the line daily and bring pins in after each load, both types last longer. If you leave pins out year-round, wood may rot but plastic will become brittle.
- Maintenance: Wooden pins can be sanded and oiled to extend life; plastic pins cannot be repaired.
- Cost: Plastic pins are cheaper upfront, but if they need replacing every season, wood may be more economical over time.
For most people, a set of cedar pins that you bring in after use will outlast several sets of plastic pins left on the line.
Common Problems and Misconceptions
A common misconception is that all wooden pins are the same. Softwood pins (like pine) rot quickly and are not much better than plastic. Look for hardwood pins, ideally cedar or acacia, which are naturally rot-resistant. Another misconception is that plastic pins are waterproof—they are, but the spring is not. Rusted springs are the #1 reason plastic pins fail.
Another issue is that people often leave pins on the line year-round. Even the best wood will eventually degrade if constantly wet. The solution is to store pins in a dry bag or box when not in use. This simple habit can double the life of any clothespin.
Cost and Environmental Considerations
Plastic clothespins are typically cheaper per pin, but they break more often, so the cost per year may be similar. Wooden pins are biodegradable and can be composted at the end of their life, while plastic pins end up in landfills. If you are concerned about environmental impact, wood is the better choice, especially if you buy pins from sustainably harvested wood.
Safety and Practical Tips
There are no major safety concerns with clothespins, but a few practical tips:
- Do not use wooden pins that have splinters—they can catch on delicate fabrics.
- If you use plastic pins in very cold weather, warm them in your hand before squeezing to avoid cracking.
- Check the spring regularly; a loose spring can pinch your fingers.
- For heavy items like jeans or towels, use pins with stronger springs—often marked as “heavy-duty.”
Also, note that some plastic pins contain BPA or other additives; if you are concerned, choose BPA-free plastic or stick to wood.
Alternatives to Traditional Clothespins
If you are tired of replacing pins, consider alternatives:
- Stainless steel clothespins – These are rust-proof and UV-resistant, but they are more expensive and can leave marks on clothes if not padded.
- Magnetic clothespins – These use magnets to grip, but they are not suitable for all lines.
- Clothespin bags – Not a replacement, but a way to keep pins dry and extend their life.
For most people, the simplest solution is to buy quality cedar pins and store them indoors.
Frequently Asked Questions
Do wooden clothespins rot?
Yes, if they are made from softwood or left in wet conditions. Hardwood pins like cedar are naturally rot-resistant and can last years if brought in after use.
Why do plastic clothespins become brittle?
UV radiation from the sun breaks down the polymer chains in plastic, making it brittle. This is accelerated by heat and cold cycles. UV-stabilized plastic lasts longer but still degrades.
Can I paint or seal wooden clothespins to protect them?
Yes, you can apply a weatherproof sealant like polyurethane or linseed oil. This helps repel water and can extend the life of the wood, but it may make the pins slightly slippery.
How long do clothespins last if I bring them in after every use?
If stored indoors, both wood and plastic can last many years. The main wear is from the spring, which eventually loses tension. With occasional spring replacement, wooden pins can last a decade.
Are plastic clothespins safe for baby clothes?
Yes, most plastic pins are safe, but ensure they are BPA-free. Wooden pins are also safe and have no chemical concerns.