11 Apr March proverb: “In like a lion, out like a lamb”
It is officially Spring! March weather is a changeable event where we can see warm spring-like temperatures or late-season snowstorms and everything in between. While spring is a welcome sight and outdoor sports begin, we are well on our way into prime banner hanging weather. But what are those March winds going to do to those hanging banners? Many believe in Wind Slits — a half moon (crescent shape) cut into a banner.
Wind slits on banners are for windy areas. It is said that crescent shapes cut into a banner (often referred to as “wind slits”) are meant to allow wind to pass through, hopefully to reduce total banner wind load. Believe it or not, they are not a good idea.
In two separate test studies, banners were put through a series of wind tunnel tests and it was visually obvious that wind holes became, in fact, detrimental to the banners due to vibration and fabric stress and they tended to increase the wind load rather than reduce it.
How can wind slits increase the load? The holes which were intended to allow wind to flow through the banner actually caused the banner fabric to ripple and catch wind which contributed to the drag factor. And the rapid “ripple” movement eventually caused the banner material to fail prematurely. It’s a win-win idea with a lose-lose outcome.
So what should you do? If you’ll be hanging a banner in an area prone to wind, here are some tips to consider:
Reinforce the edge: Adding strength to the edge is a good first line of defense. This is done in the manufacturing process where nylon webbing is added to the perimeter of the banner. This provides a firm foundation for the grommets to be fastened and significantly increases the overall strength of the banner.
Tension and Secure: Make certain the banner has tension enough to where it is taunt and securely fastened using ALL of the provided grommet locations. This helps the banner carry the wind load as it is distributed evenly to all anchor points.
Inspect: Regular inspection is a must. Check the overall tension and all fasten locations. Make adjustments as needed.
Another thought – Instead of vinyl banner, consider using a mesh material which allows air to pass through the entirety of the banner. And even with a mesh banner, the points above (reinforce the edge, tension and secure, and inspect) are still important for longevity.