To translate this web page, please choose a language from the dropdown menu >

Du-Lite Frequently Asked Questions, FAQs.

You will find answers to many common questions about Du-Lite and our products and services below. Please review the list below to find the answers to your questions. If after browsing the FAQs you still need our help, please email or call us at 860-347-2505.

Q: How long should I leave my parts in a black oxide tank to achieve the best protection and color?

A: Most parts will require a processing time of 15-30 minutes for best color and corrosion resistance.

Q: If I heat my black oxide tank to 285ºF and the tank is boiling, can I shut the heat off and run my parts for several hours?

A: The heaters/gas burners must remain on to maintain the boil while processing parts.

Q: How do I maintain the proper boiling temperature while black oxiding?

A: A black oxide tank with an operating temperature of 285ºF is maintained by constantly checking temperature and adding salts to raise it’s boiling point if needed. If you need to lower the boiling point add small amount of cold water to the top of tank. Do not add cold water under the solution as it will cause a violent eruption into the air and onto the floor.

Q: Should I leave my hand held thermometer in the tank while continuously checking temperature?

A: Steam will ruin the thermometer if left in tank. Check the temperature continuously however removing once you view the temperature, rinse off the stem in the cold water rinse tank.

Q: How long will my black oxide bath last before I have to change it?

A: Many black oxide baths will last between one and five years. It is suggested to add fresh salts daily to restore the salts which attach to the parts that are removed during the black oxide process.

Q: What is the brown scum which appears at the top of the black oxide tank?

A: The brown scum is impurities from the chemicals along with grease and oil, which comes to the surface during processing. Remove the brown scum with a stainless steel strainer and place into a plastic pail and dispose of according to local, state, and EPA regulations. It is suggested to skim brown scum at the beginning of the day and again half way through the day.

Q: If I put a large heavy part in the black oxide tank and the solution stops boiling, will the part blacken properly?

A: A black oxide bath which is not boiling will not black oxide parts. Large heavy parts may have to remain in the solution for a longer period until the solution starts to boil again. At that point, you can start your processing timer for a minimum of 30 minutes.

Q: If I leave my part in the black oxide bath longer than usual will it build up a heavy coat onto the metal?

A: Black oxide does not add to the dimensions of the parts by building on the surface of the metal. Black oxide penetrates no more than 90-millionths into the metal surface, whether you leave the part in for 15 minutes or hours.

Q: Should I plug the barrels to my firearms before going into the black oxide processing tank?

A: It is not necessary to plug the barrels to the firearms during the black oxide process, as there will be no buildup inside the barrels that will harm the accuracy or hurt the firearm in any way. Once the gun is fired, the black color will be removed.

Q: What should I do if some of the black oxide solution gets on my skin?

A: Rinse immediately with clean cold water, then pour white vinegar on the affected area then rinse again. The vinegar will neutralize the chemical which is burning you. Always wear eye protection, plating gloves, long sleeve shirt and coveralls when using the black oxide system.

If you would like to speak to us directly we would welcome the call. You can reach us
by phone at 860-347-2505, or if you'd prefer email us.