To unrust a screw effectively, you often need to loosen the rust bond that holds it in place, using methods like applying heat or using rust-penetrating lubricants.
Dealing with rusty screws can be a common frustration in DIY projects or repairs. Rust can effectively seize a screw, making it impossible to turn with a screwdriver. The goal of "unrusting" is typically to break this bond and allow the screw to be removed or cleaned.
Methods for Unrusting and Loosening Rusty Screws
Several techniques can help you unrust or, more accurately, break the rust seal on a stubborn screw. Combining methods can often be the most successful approach.
Using Heat
One effective method involves using heat to cause the metal to expand, which can crack the rust seal.
- Reference Method: To do this, simply take a lighter or small torch on low to moderate heat and hold it up to the screw for 5-15 seconds. Be careful — it's hot. The heat from the flame can cause the metal of the screw to expand, which might break up some of the rust sealing it to the material in which it's screwed.
This thermal expansion and contraction can be surprisingly effective at loosening the grip of rust. Always exercise caution when using open flames and be aware of surrounding materials that might be flammable.
Applying Penetrating Oil
Another popular method is using a penetrating oil, specifically designed to seep into tight spaces and dissolve rust.
- Apply a generous amount of penetrating oil to the screw head and threads.
- Allow the oil to soak in for several minutes, or even hours, depending on the severity of the rust. Tapping the screw gently with a hammer (without damaging the head) can help the oil penetrate.
- Attempt to slowly turn the screw. You may need to reapply oil and wait if it doesn't budge initially.
Common penetrating oils include products like WD-40 (though some argue dedicated penetrants work better), PB Blaster, or Kano Kroil.
Using Rust Removers
Chemical rust removers can dissolve the rust itself, weakening its hold.
- Liquid rust removers (like naval jelly or specialized solutions) can be applied directly to the screw.
- Follow the product's instructions carefully, as these chemicals can be corrosive.
- Allow the remover to work for the recommended time, then attempt to unscrew.
These are often useful for cleaning up threads or surfaces after the screw is removed, but can sometimes help loosen a seized screw initially.
Other Mechanical Methods
Sometimes, a combination of force and technique is needed.
- Impact Driver: A manual or electric impact driver can apply a sudden rotational force while simultaneously pushing down, which helps break the rust bond.
- Grip Enhancement: If the screw head is damaged, using locking pliers (Vise-Grips) to grip the head or shank can provide more torque.
- Cutting a Slot: For screws with damaged heads, cutting a new slot with a hacksaw or rotary tool can allow you to use a flathead screwdriver.
Comparing Methods
Here's a quick comparison of common methods:
| Method | Description | Pros | Cons |
|---|---|---|---|
| Heat (Torch) | Applies focused heat to the screw | Quick, effective for thermal expansion | Risk of fire/damage to surrounding material, requires torch |
| Penetrating Oil | Liquid seeps into rust and dissolves bond | Easy to apply, less risk of damage | Requires soaking time, multiple applications may be needed |
| Rust Remover | Chemical dissolves rust | Good for severe rust, cleans threads | Can be corrosive, requires careful handling, needs time |
| Impact Driver | Applies sudden force | Effective for stubborn screws | Requires specific tool, can damage screw head/material if misused |
Important Note: Always use the correct size screwdriver or bit that fits snugly into the screw head to avoid stripping it further. Applying firm downward pressure while turning is crucial.
By carefully applying one or a combination of these methods, particularly utilizing the heat method mentioned in the reference, you can effectively break the rust bond and remove a seized screw.
