@Harry Anderson The reason your current bath is turning green, cloudy, and losing its strength is completely normal. As a sulfamic acid solution works, it dissolves copper and zinc oxides (the green patina and gunk) from the inside of the horns. Over time, the solution becomes saturated with these metal ions, which turns the bath green. Furthermore, sulfamic acid slowly hydrolyzes into ammonium bisulfate over time—especially if the bath is kept warm—which naturally reduces its effectiveness. ​If you are looking for alternatives or reasons to change/upgrade your process, here is a breakdown of what we use in the shop: ​Pure Sulfamic Acid (H_3NSO_3): You can buy bulk technical-grade sulfamic acid powder. It’s exactly what gives Z19 its cleaning power. It's excellent because it creates highly soluble calcium salts, meaning it completely flushes out lime deposits and tarnish without leaving a white residue. It is much less aggressive to the underlying brass than hydrochloric acid, though it can still aggressively expose weak, porous solder joints if left in for too long. ​Citric Acid (C_6H_8O_7): Many tech shops have switched completely to a warm 5% to 10% citric acid bath. It is an organic, biodegradable alternative that is safer to handle, easier to dispose of legally, and works beautifully for general de-liming and brightening of both brass and silver without being as harsh on the tech or the metal. ​Phosphoric Acid (H_3PO_4): Another option, though more commonly used in industrial "rust kill" products or very specific heavy-duty cleaning. It's great for removing tough scale, but requires very strict handling, dilution, and precise timing to avoid dezincification of the brass. ​Whichever acid route you choose to replace your Z19, just remember the golden rule of the repair shop: always follow up the acid bath with a thorough rinse and an alkaline neutralizing bath (like a sodium bicarbonate/baking soda mix). This stops the residual acid from remaining trapped via capillary action inside the solder joints and slide seams, preventing corporate rot from the inside out.

Gregory, there isn't one single "magic" solution because it depends on whether you are doing a deep chemical clean of the interior or a cosmetic clean of the exterior, especially when dealing with silver plate versus raw or lacquered brass. Here is the professional standard approach we use in the shop: ​ 1. For Internal Cleaning & De-liming (Both Brass and Silver): ​Citric Acid (C_6H_8O_7) or Sulfamic Acid (H_3NSO_3): For a full chemical clean to remove mineral deposits (scale), green gunk, and calcification from the inside of the tubes, a warm 5% to 10% Citric Acid bath or a Sulfamic Acid bath (like Ferrees Z19) is the industry best practice. ​The Rule: Both acids are safe for the underlying metal of both brass and silver horns if the immersion time is kept short (usually 3 to 10 minutes). Crucial step: You must always submerge the horn in an alkaline neutralizing bath (water mixed with baking soda) right after the acid dip, followed by a thorough flush with fresh water. If you don't neutralize it, residual acid will stay trapped in the slide seams and solder joints, causing internal corrosion over time. ​ 2. For Exterior Cleaning & Tarnish Removal (Specifically Silver): ​Avoid Harsh Acids for Tarnish: While acid baths clean the dirt, they do not efficiently remove silver tarnish (silver sulfide, Ag_2S). ​Silver Polishes: For silver horns, use a dedicated, low-abrasive silver polish (like Hagerty, Wright's Silver Cream, or Tarni-Shield). These contain mild abrasives and tarnish inhibitors that clean the silver without wearing down the thin plating. ​Ultrasonic Cleaning: If you have access to an ultrasonic tank, a specialized mild ultrasonic soap formulated for silver and brass is the absolute gold standard. It removes the tarnish and dirt via cavitation without the need for aggressive scrubbing or harsh chemicals. ​ 3. For Daily/General Cleaning: ​Degreasing: Before any acid bath, always strip the horn down and wash it with a good degreasing soap (like Simply Green or Dawn dish soap) and warm water using flexible cleaning snakes and brushes. This removes the old valve oil and slide grease so the acid solution can actually reach the metal and do its job.

@Irma Kreiten Welcome to BMA, Irma! 🎺🔥 You’re exactly the kind of person this community was made for. There’s a LOT coming soon — repair techniques, troubleshooting, instrument mechanics, tools, and real workshop knowledge. Glad to have you with us from the beginning! 🙌