Elevator Rope Rouge Is not Rust: The Truth About Reddish Dust on Elevator Ropes
Figure 1 – Redish dust on elevator equipment. This is not corrosion related.
Introduction
As an elevator mechanic enters a machine room and observes a reddish substance on elevator ropes, there is an assumption that water or a high level of humidity has made contact with the traction ropes and they are corroding. An expensive claim by the service provider sometimes ensues followed by a dispute. The reality can often be considerably different.
What Proper Rope Lubrication Looks Like
The elevator code A17.1-2022 section 8.6.4.1.2 requires that “steel ropes shall be lightly lubricated. Precautions shall be taken in lubricating suspension steel wires ropes to prevent the loss of traction. Lubrication shall be in accordance with instructions on the rope data tag (see 2.20.2.2.2(n)) if provided”.
Wire rope lubricants have two functions being:
To reduce friction between the individual wires;
To provide corrosion protection and lubrication in the core and inside wires and on exterior wires.
There are generally two types of lubricants, penetrating, and coating. Penetrating lubricants contain a petroleum solvent which carries into the core then evaporates leaving behind a heavy lubricating field to protect and lubricate each wire and each strand. Coating lubricants penetrate slightly, sealing the outside of the cable from moisture and reducing friction between the wires.
Figure 2 – properly lubricated steel hoist rope
Since most wire ropes fail from the inside, it is important to make sure that the center core receives sufficient lubricant. Over time, the original factory lubrication wears off, so ropes need to be re-lubricated regularly, typically once per year or every 250,000 elevator cycles. Whichever comes first.
It’s important to use the correct rope-grade lubricants. Too thick, and it can trap dirt; too thin, and it won't provide lasting protection. The key is using a lubricant that penetrates but doesn’t attract buildup.
When Lubrication Fails: Fretting and Rouging
Without proper lubrication, elevator ropes suffer from internal wear. Each time the elevator travels, the individual steel wires inside the rope rub against each other. This phenomenon, known as fretting, produces microscopic metal particles. When these particles are exposed to air, they oxidize into a fine reddish dust. This is what we call rouging.
Figure 3 – Rouging dust on machine room floor
While it might look like rust from water exposure, rouge is a mechanical issue. It's evidence that internal abrasion is occurring. And here’s the bad news: once fretting begins, the damage is irreversible. Applying a lubricant afterward may slow the progression, but it won’t undo the internal wear. Rouge is your warning sign that the rope is wearing out from within.
Humidity and Water: The Hidden Accelerators
Figure 4 – Wet elevator pit
Water and humidity still play a role in rope degradation, but often in a secondary way. If an elevator pit has standing water or excessive dampness, the humidity in the hoistway can exceed 90%. This causes elevator hoist ropes with natural fiber cores to absorb moisture. As a result, the cores swell, which forces out internal lubrication. Later, when the environment dries out again, the fiber core will contract and become brittle. This weakened state increases the risk of internal friction and fretting, making rouge formation more likely. In this case, it’s not just the water, it’s what happens after the ropes dry that does the real damage. In such a case, it is critical that you work with the elevator service provider to lubricate the hoist ropes shortly after pits have dried out.
This would be considered an extra fee to typical service contracts.
What do corroded ropes look like?
The above discussion focuses on rouging. But there are many instances where water will travel down the hoistway due to a broken water pipe or activated sprinkler head at one of the floors causing considerable damage to the elevator equipment. While figures 1 and 3 show a reddish dust on the ropes and surrounding elevator equipment, a corroded rope looks considerably different. Figure 5 indicates a red blistering residue between the rope strands. This residue, unlike rouging dust, tends not to spread onto the surrounding elevator equipment.
Figure 5 – corroded rope
In the above case, the hoist ropes have to be replaced within a short period of time (1-3 months) and the cost is not covered by the elevator service contract. These costs can be significant (from $15,000 to $75,000) depending on the number of ropes, rope diameter, and number of stops served by the impacted elevator.
The Impact of Machine Room Ventilation
Most elevator machine rooms are ventilated to manage heat, air quality and to provide a friendly environment to elevator technicians. However, one must ensure that ventilation systems do not blow directly onto the ropes since this will accelerate the evaporation of rope lubricants. This will leave the ropes dry, exposed, and vulnerable to internal friction.
Figure 6 – Incorrect location of an AC unit in an elevator machine room
Technicians working in buildings with strong mechanical ventilation should increase inspection frequency and consider more frequent re-lubrication. Dry air may not seem like a hazard, but over time it creates the same risks as neglecting lubrication altogether.
Maintenance Matters
Technicians should routinely inspect ropes for reddish dust around sheaves or motor beds. If the rope feels dry or leaves no oily residue on a cloth, it’s usually time to re-lubricate.
Maintenance schedules should be adjusted for high-use elevators and machine rooms with strong airflow or moisture problems. Ropes showing signs of rouging should be evaluated using the ASME guidelines for wire breakage. In many cases, the presence of rouge warrants planning for rope replacement.
Conclusion
Rouge may look like a minor issue, but it's a visible clue that internal damage is occurring. It’s not rust, it’s a mechanical problem caused by lack of lubrication and internal wear.
Understanding the conditions that lead to rouging, like water exposure, dry air, or missed maintenance, can help building managers and elevator professionals extend rope life and reduce safety risks. Don’t ignore the red dust. Take it seriously, and act before it's too late.
Please contact our office at 416-961-3938 or at Toronto@KJA.com in case of further questions.