If your neon sign looks dim or has dark spots, don’t worry—it’s a common issue called mercury migration, and it’s usually an easy fix!

How Neon Signs Work

Neon signs that glow blue, white, and some shades of green or purple contain a small amount of liquid mercury inside the glass tube.

When the sign is turned on, electricity excites the mercury vapor, producing ultraviolet (UV) light. This UV light interacts with the phosphor coating inside the tube, creating the bright colors you see.

Most of the time, mercury stays in a vaporized state, ensuring an even glow across the entire sign.

Why Does Mercury Migration Happen?

Sometimes, instead of staying vaporized, tiny droplets of liquid mercury can form and settle inside the tube. This can happen due to:

• Shipping & Movement – Vibrations during transport can cause mercury to settle in one spot.
• Temperature Changes – Cold temperatures can cause mercury to condense into liquid, while heat may move it away from where it’s needed.
• Gravity & Positioning – If a neon sign is stored or mounted at an angle, mercury may collect in certain areas instead of staying evenly distributed.
• Long Periods of Being Turned Off – When a sign hasn’t been used for a while, mercury can settle, leading to dim sections when turned back on.

How to Spot and Fix the Problem

If part of your neon sign looks dim or dark, take a close look at the unlit section. You’re searching for a tiny mercury dot, which may be as small as a period in a newspaper or look like a tiny silver bead inside the glass.

Fixing It is Simple!

1. Find the Mercury Dot – Look closely at the dim section of the tube for a small silver speck.
2. Gently Tap the Tube – Using your finger, lightly tap the glass near the mercury dot to help move it.
3. Guide It to the Electrode – Keep tapping until the mercury dot reaches the metal electrode at the end of the tube.
4. Watch It Light Up – Once the mercury touches the electrode, your sign should fully illuminate again!

This helps the mercury re-vaporize, allowing the neon sign to work properly again.

Here are some videos that show what to do:

Most of the time, this simple fix restores the brightness of your neon sign instantly. If you still have issues, feel free to contact us for further assistance