What is Threadlocker?

Threadlocker is an adhesive for nuts, bolts, and screws to lock them in place and avoid loosening caused by stress and vibration. They replace traditional mechanical washers and fasteners. They are chemicals that harden without needing air that form a strong film in the gaps between the thread of the connection, locking it in place. Threadlockers are available in different versions with different hardening times, maximum strength, and temperature ranges.

Table of contents

• Threadlocker properties
• Selection guide
• Common applications
• How do you apply threadlocker?
• How do you remove threadlocker?
• FAQ

Threadlocker properties

A threadlocker works by filling the gaps between threaded metal parts, curing to form a solid, thermoset plastic that prevents loosening, leakage, and corrosion due to vibration and other forces.

How long threadlocker takes to dry depends on several factors, including the type of threadlocker, the ambient temperature, humidity levels, and the materials being bonded.

Threadlockers should exhibit the following properties:

• Fast cure speed at room temperature
• Chemical compatibility with acids, alkalis, and solvents
• Vibration resistance
• Good consistency for even application

Liquid threadlockers are commonly used for their ease of application and ability to penetrate threads.

Read our Loctite threadlocker color explanation article to learn more about Loctite products. Read our sealing and adhesives overview article for all different types of sealants and adhesive products.

Selection guide

Consider the following criteria when selecting a threadlocker for your application:

1. Media: The media coming in contact with the threadlocker should be chemically compatible. Common examples of compatible media for threadlockers include metals like steel and aluminum, as well as plastics such as nylon and polycarbonate. Additionally, they are often compatible with oils, lubricants, and various solvents.
2. Curing speed: The full curing time of the threadlocker usually takes about 24 to 36 hours, whereas the handling cure time can be 1.5 to 30 minutes depending on the type and strength of the threadlocker.
3. Approvals: Threadlockers come with different approvals for use in different applications. Low-strength Loxeal threadlocker and high-strength Loctite threadlockers are available with gas application approval. ANSI/NSF certifications are for drinking water and food-safe threadlockers.
4. Temperature: Temperature can affect the performance of the threadlocker. High-temperature threadlockers are available to use for high-temperature applications.
5. Torque:There are low-, medium-, and high-strength threadlockers available. Low-strength threadlocker is used for applications where the fasteners may need to be adjusted, removed, or disassembled frequently without requiring excessive force. The recommended threadlocker for small screws is often a low-strength one, in order to avoid damage during disassembly. Medium-strength threadlocker is used for applications where a balance between holding power and removability is required. It provides a stronger bond than low-strength threadlocker, but it can still be disassembled using tools. High-strength threadlockers are suitable for applications that do not require breaking the seal in the future.
   1. Low strength: Can be disassembled with force.
   2. Medium strength: Can be disassembled with high force.
   3. High strength: These are considered permanently locked and can only be removed using specialized chemicals.

Threadlocker chart

The following chart provides information on different brands, strengths, and specifications:

Strength	Brand	Color	Max Thread Size	Cure Speed (handling cure speed/ full cure speed)*	Temperature range (°C)	Breaking Torque (Nm)	Viscosity (+25°C - mPa s)	Approval
Low Strength	Loxeal	Purple	M24	15-30 mins/ 24-36 hrs	-55 to 150	5 to 8	800 - 1400	Gas
	Loctite	Purple	M36	10-300 min/3-72 hrs	-55 to 150	4 to 14	900 - 1500	-
Medium Strength	Loctite	Blue	M36	5-30 mins/0.5-72 hrs	-55 to 180	5 to 25	1300 - 3000	-
	Loctite (Wax Stick)	Blue	M50	15 mins/4-72 hrs	-55 to 150	8 to 32	-	-
High Strength	Loxeal	Green	M5	10-20mins/ 24-36 hrs	-55 to 150	11 to 25	10 - 20	-
	Loxeal	Green	M20	10-20mins/ 24-36 hrs	-55 to 200	25 to 35	450 - 650	-
	Loxeal	Green	M25	10-20mins/ 24-36 hrs	-55 to 200	25 to 35	450 - 650	-
	Loctite	Green	M6	15 – 60 mins/3-6 hrs	-55 to 150	10 to 40	20 - 55	-
	Loctite	Green	M20	5 - 30 mins/3-72 hrs	-55 to 150	5 to 46	400 - 600	Gas
	Loctite	Green	M20	5 - 30 mins/3-72 hrs	-55 to 180	5 to 46	400 - 600	-
High Strength	Loctite (Wax Stick)	Red	M50	5 min/ 8 – 168 hrs	-55 to 150	10 to 50	-	-
	Loctite	Red	M80	5 – 60 min/1 – 72 hrs	-55 to 200	23 to 30	4000 - 15000	-

*medium dependent

Common applications

A wide range of industrial and residential applications use threadlockers. Some applications include:

• Water pipeline assemblies
• Gas line assemblies
• Automotive maintenance
• Aerospace assemblies

How do you apply threadlocker?

The following steps are involved when applying a threadlocker:

1. Make sure the surface is clean, dry, and free of grease.
2. Choose the correct threadlocker type according to the application.
3. Apply the threadlocker evenly throughout the thread surface.
4. Assemble the fastener and leave for curing.

How do you remove threadlocker?

The following steps are involved in removing the threadlocker:

1. Heat the fastener for a couple of minutes.
2. Use a hand or wrench to remove the bolt.
3. If applying a new threadlocker, clean the bolt and apply the new threadlocker to the threads and reinstall.

You can learn more about wrenches in our wrench buying guide.

FAQ

What is threadlocker?

Threadlocker is an adhesive used to lock bolts, studs, nuts, and screws and prevent accidental loosening of the fasteners due to exposure to stress and vibration.

How to use threadlocker?

To apply the threadlocker, apply a small amount on the thread of the fastener before installation. Once it is dry, it will form a bond and hold the fastener in place even when exposed to vibrations.

Is threadlocker glue?

The threadlocker can be used as a glue. However, the adhesive bond may differ for different types of threadlockers. Blue, green, red, purple, yellow color-coded threadlockers are available, with each having different adhesive strength.

Is threadlocker permanent?

Red or green threadlocker (high strength) are often called permanent threadlocker for their high adhesive strength.