FAQ

No. Metal Rescue will penetrate dirt and oil.  However, pre-cleaning metal parts is recommended before soaking in Metal Rescue and detergents are more economical and are designed to remove various contaminants.The removal of anything that could act as a barrier to Metal Rescue making its way to the surface of the metal will speed up the rust removal process and extend the life of the Metal Rescue.   Because Metal Rescue is not an acid, items such as cosmoline, heavy greases, and similar materials, should be removed.

Metal Rescue will remove iron oxide (rust) from ferrous-based substrates in 5 minutes to 48 hours depending on the degree and age of the rust. It will remove zinc phosphate, blueing, browning, and other oxide finishes in about 20–40 minutes immersion time. It also brightens copper and copper based alloys such as brass and bronze.

Metal Rescue will not remove anodizing, chrome, nickel, powder coating, and paint (as long as rust hasn’t formed under paint and paint does not contain iron oxide in pigment).  See response to Is Metal Rescue Safe to Use on Painted Surfaces? question below for additional details.

 

Yes, Metal Rescue will not remove or harm the vast majority of paint coatings, with a few exceptions.

#1. If there is a layer of rust has formed under the paint some of the paint coating will be lost as Metal Rescue  removes the rust and therefore the paint on top of the rust.
#2. Some paints and inks (typically red/orange), especially old paints, may use iron oxide pigment.  Metal Rescue has been engineered to remove iron oxide in all forms, therefore it may dissolve the pigment in these types of paints.
#3. Painted metal items with flaking or cracking surfaces or chipping/deteriorating paint or coatings may not be suited for prolonged soaking–whether it is Metal Rescue or plain water–and may experience unexpected damage.

We strongly advise that “when in doubt, test it out.”  Test a small, unseen area on the items before proceeding with your project.  Download our Metal Rescue Rust Remover Vintage Painted Items Tip Sheet for additional information.

Metal Rescue is a rust remover designed for iron and steel. It is safe on metals other than iron and steel as long as they are not left in a Metal Rescue soak too long. Metal Rescue will remove some oxides from copper, brass, nickel and certain aluminums, however, immersion time is critical. The length of immersion time is dependent upon the amount of oxidation present and alloy composition. It is recommended that the following metals be checked approximately every hour so as not to damage the surface under the oxidation layer: aluminum, brass, copper, chrome, gold, lead, nickel, silver, titanium, tungsten, solder or solder points.

No. It will not harm rubber, plastic, clothing, glass, and other surfaces that are unharmed by water alone. However, as with any materials soaked in a liquid, do not soak these materials longer than you would have them soak in water.

Metal Rescue may leave a black film on some parts. The black is from iron oxide II, often referred to as black oxide. Black oxide is a corrosion inhibiting film that is a more stable state of oxidized iron. It is not detrimental to the metal surface and is only cosmetic in nature. It can form on certain steel alloys and high carbon steel when left in Metal Rescue for longer periods of time. For these metals, reducing the time that the part is immersed in Metal Rescue bath will minimize the black film.  Much of the black oxide film can be removed by rinsing with mild detergent or wiping with a cloth–it is easiest to do so immediately after removing parts from Metal Rescue and before the parts dry.  The black oxide becomes more difficult to remove from metal parts that have soaked for long periods of time.  It is best to soak rusted parts only as long as needed to remove the rust.

Some steels may develop a dull grey finish on polished surfaces. This is attributed to a phosphate-like coating that has formed and can typically be removed using abrasive pads or similar substances. This can be minimized by checking metal parts and removing from them from Metal Rescue bath when rust has been removed. Parts should be soaked in Metal Rescue only for as long as needed to remove rust.

Metal Rescue is not recommended for use on magnesium or magnesium alloys.

Metal Rescue only works in the liquid form.  Metal Rescue is designed to be used as a bath or a soak–to work effectively Metal Rescue must remain in constant contact with the metal you are trying to de-rust.  The use of other application methods such a spray or brush will not produce the desired results–Metal Rescue will dry before rust removal is complete.  However, Metal Rescue is effective in removing rust if continuously sprayed onto the surface until the rust has been dissolved. Typical operations are continuous spray washers with the Metal Rescue bath being re-circulated. For specific information about the re-circulating pump method, please contact Workshop Hero™ at 1-800-365-1117.

 

A smooth, absorbent material can be soaked with Metal Rescue and applied to the rusted area (the texture of the material is key–do not use a material with a pattern or texture as it could be transferred to the rusty item). The material will need to be re-saturated every couple of hours and kept covered with plastic wrap to prevent evaporation and drying.  An alternate method for removing light rust is to scrub the rusted surface with Metal Rescue–rusted area must remain in wet contact with Metal Rescue bath to obtain desired results. While this is not the intended form to use Metal Rescue, it is still much safer than scrubbing with acids and alkalis.

One gallon of Metal Rescue will remove approximately a ½ pound of dry rust. That is equivalent to removing rust from approximately 300 pounds of moderately rusted steel. For reference, 1 gallon of Metal Rescue will remove rust from approximately 10 square feet of moderately rusted steel.  If any of the Metal Rescue bath evaporates, simply replace it with fresh tap water to original level.

Metal Rescue darkens in color as it is working.  As bath becomes “exhausted,” it will turn completely black and rust removal rates will significantly decrease. The specific gravity will change from 1.02 to 1.06.

One way to determine if, or when, Metal Rescue has become “exhausted” and is no longer able to remove rust is to measure its specific gravity (specific gravity will change from 1.02 to 1.06).  While there are several ways to do so, we suggest the use of a hydrometer.   A hydrometer is a scientific tool used to measure specific gravity of liquids (ratio of the mass of a liquid to the mass of an equal volume of pure water).  Hydrometers are commonly used for home brewing, wine making, and by salt water aquarium enthusiasts.  They are available at a cost of approx. $5-$15.

 

Metal Rescue will continue to work even after changing color. The bath darkens due to the iron oxide particles removed from the iron/steel.  When removing rust from a heavily rusted item, the bath will turn darker.  Metal Rescue will cease to be effective when it becomes completely black.

Yes. The particles of rust removed from the rusty metal part are “held in suspension” in the Metal Rescue bath, which causes Metal Rescue to change in color from clear to black.  Typically, there will only be a small percentage of rust particles on the bottom of the soaking tub compared to the amount of rust removed from the metal part(s).  Filtering or straining loose rust from Metal Rescue before storage will prevent the active ingredient in Metal Rescue from being exhausted. This will not reactivate the used Metal Rescue but instead preserve the corrosion removal properties.   Use a filter such as cheese cloth or a paint filter and store used Metal Rescue separate from unused Metal Rescue.

Metal Rescue may leave a black film on some parts if metal parts are left in bath too long (over 24 hours).  The black is from iron oxide II, often referred to as black oxide. Black oxide is a corrosion inhibiting film that is a more stable state of oxidized iron. It is not detrimental to the metal surface and is only cosmetic in nature. It can form on certain steel alloys and high carbon steel when left in Metal Rescue for longer periods of time. For these metals, reducing the time that the part is immersed in Metal Rescue bath will minimize the black film.  Much of the black oxide film can be removed by rinsing with mild detergent or wiping with a cloth–it is easiest to do so immediately after removing parts from Metal Rescue and before the parts dry.  The black oxide becomes more difficult to remove from metal parts that have soaked for long periods of time.  It is best to soak rusted parts only as long as needed to remove the rust.

Metal Rescue works best when the bath is in direct contact with the metal.  Bulk parts that are lying on top of each other may need to be rotated, agitated or moved in order to ensure adequate contact with Metal Rescue bath occurs.

Metal Rescue contains no VOCs, solvents, acids or other hazardous ingredients. Spent (used) Metal Rescue is biodegradable and in most locations directly sewerable unless hazardous waste (certain oils, paints, heavy metals, etc.) is introduced into the solution. It is recommended that Workshop Heroes using Metal Rescue check local and federal disposal requirements.

To accelerate the rust removal process, heat Metal Rescue up to a temperature of 150° F (70°C).  Remember, Metal Rescue is a water-based liquid and therefore operates differently than an acid or other traditional rust remover.  A useful analogy is of very soiled and dirty dishes. It would be very difficult to remove heavy grease or sticky substances in cold, soapy dish water compared to warm soapy dish water. Because Metal Rescue is water-based it functions in a similar way.  This example is offered only as an analogy — Metal Rescue does not require heat to work-but it does require that the temperature of the bath remain at room temperature or above.  Operating temperatures for Metal Rescue® are 68°F (20⁰C) to 150°F (65⁰C).

 

 

Move the Metal Rescue to a warmer area and let stand to thaw. Once completely thawed, use as directed–making sure that Metal Rescue bath is at a minimum temperature of 68°F (20⁰C).

Metal Rescue is completely water miscible and easily rinsed off. Use warm clean water to rinse off parts and dry thoroughly after.

While Metal Rescue is “safe on everything except rust”, moderation is key.  If Metal Rescue bath is left in a metal container for a long period of time, two things will happen:

#1. The metal container may develop a black film on it due to the formation of iron oxide II, often referred to as black oxide. Black oxide is a corrosion inhibiting film that is a more stable state of oxidized iron. It is not detrimental to the metal surface and is only cosmetic in nature. However, the main concern with this is that it will exhaust or use up Metal Rescue’s rust remover capabilities.
#2. As a metal (metal container) is in contact with Metal Rescue for extended periods, carbon can be pulled to the surface, causing the container to become darker. This phenomenon will especially occur with high carbon steel and certain alloys.

We recommend using a plastic container when soaking parts in Metal Rescue.