Where theworld gathers for metal finishing
Q&As since 1989
-----
Paint Stripping in Dip Tanks
Q. I am an architect/contractor specializing in restoration of historic homes. I have tried a bunch of different methods to clean and prep wood doors and trim. They all prove too caustic or time intensive. The only thing that seems to get the job done is having items dipped. As my company has grown, I have more and more stripping needs, and the cost of sending items out is prohibitive. I have decided to set up my own stripping operation. I would like to know some resources and get some advice on the best methods to strip architectural wood doors and trim. My research says hot tank with an aqueous alkaline solution and mechanical agitation followed by water wash-down may be best. Looks like there are several products on the market now that are relatively safe and environmentally friendly.
I would appreciate any thoughts or suggestions.
Thanks,
preservation and development - Knoxville, Tennessee, USA
2006
A. Be careful. I was sucked in by the chemical supplier's claims. I got all the good news and none of the bad. What do you do with spent stripper and how do you contain and have zero discharge of water used for wash down of the stripped material?
I just spent $1300 to have 3 barrels of sludge from the stripper hauled away by an approved haz material handler. I now have lots of barrels of used but still usable stripper. The EPA considers it all waste and I can't even move it myself.
I have had to cease all stripping operations until I have an economical solution to the use of the stripper, primarily the disposition and handling of the wash down water.
Larry Johnson
- Key West, Florida
2006
Q. I have about 4,000 pounds of extruded aluminum, and cold rolled mild carbon steel that all need to be stripped of TGIC powder coat. We decided the most cost effective solution for us is to immerse the parts into a 4'x8' heated bath that will hold 300 gallons - 70% water mixed with 30% caustic soda
[affil links]
flakes.
I would like to know if there are any blueprints or plans for building a tank to house caustic soda
[affil links]
& water mix with all plumbing & material specs., dimensions, safety requirements, etc.
- Philadelphia, Pennsylvania, USA
January 3, 2013
A. Hi Krikor. Although certain individual items like the heaters are catalog items, metal finishing tanks are custom designed. You might be able to find an applicable set of prints from a used equipment dealer, since they tend to accumulate piles of files when they buy up the old equipment.
You might be best off retaining a consultant to put this plan together for you. And please test your plan of stripping powder coating from aluminum with heated caustic before building the system! :-)
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
January 4, 2013
A. Sir:
A bare steel tank is okay for construction. You cannot strip paint from aluminum using caustic soda
[affil links]
(NaOH). This strong base will dissolve aluminum and gas off hydrogen. You really do not want to do this because it is a violent exothermic reaction.
Regards,
Galvanizing Consultant - Hot Springs, South Dakota, USA
Q. I need a book recommendation on the design and proper management of a caustic soda tank. The tank will be used to strip paint from motorcycles frames and other intricate surfaces, which are being repainted after the coating has failed. Proper design, safety, and disposal of the waste products is important to me. I've been unable to find much information on this topic as of date.
Adam Princemotorcycle customizing shop - Rochester, New York, USA
May 29, 2013
Q. Larry Johnson, could please relate more details from your experience? Does not all paint stripping methods have the possibility of generating hazardous waste depending upon the composition of the stripped paint? With primers that contain heavy metals being the worst offenders? (Ex. zinc chromate, lead (II,IV) oxide).
Adam Prince- Rochester, New York, USA
June 4, 2013
A. Hi Adam. Larry is certainly welcome to reply, but he probably won't. This is a public forum which is not only for camaraderie and current chats, but which we maintain as a permanent reference. So some postings are years old and people have moved on.
In reply to your question, as it was once put very succinctly by a New Jersey governor, " 'Toxic' is a matter of statute, not opinion". In some cases the wastes from industrial activities like painting and plating are "categorically" deemed hazardous wastes, i.e., you don't test them to determine if they are hazardous; rather, they are hazardous waste by law. Further, a stripper may be hazardous even if the paint that you stripped with it wasn't.
I'd suggest that you speak both to a vendor of environmentally friendly strippers, and to the government regulating agencies that are licensing your activities and to whom you are releasing any wastewater, if applicable. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
June 5, 2013
Q, A, or Comment on THIS thread -or- Start a NEW Thread