A sealing bath is the step that decides whether the colour you paid for is still there two summers later. This nickel acetate-based sealing agent closes the pores of the anodic film on aluminum and aluminum alloys after electrolytic coloring or dyeing. It arrives as a dark green, weakly acidic liquid that goes straight into the tank — no pre-dissolution, no separate make-up vessel — and it works in the medium temperature band rather than at a near boil.
On an aluminum anodizing line the sequence runs anodize, colour or dye, seal, rinse, dry. Sealing hydrates the oxide and closes the columnar pores, which is what keeps dye in the film, blocks moisture and gives the part its resistance to neutral salt spray. It also decides how the finished surface reads on the bench and in the hand — a part either looks finished or it looks sealed in a hurry.
Shops in industrial metal plating and surface treatment move to a medium-temperature sealer when they want a properly closed film without committing a tank to boiling temperatures. Heating, tank wear and drag-out all stay easier to manage, and the sealing stage fits inside a normal shift. Control comes down to four things: concentration, pH, temperature and time in the bath.
| Parameter | Value |
|---|---|
| Product name | Phoenix Seal 149-T |
| Product type | Nickel acetate-based sealing agent |
| Physical form | Dark green, weakly acidic liquid |
| Suitable substrates | Anodized aluminum and aluminum alloys |
| Application | Sealing anodized films after electrolytic coloring or dyeing |
| Concentration | 30–50 ml/L (optimal range 35–45 ml/L) |
| Bath temperature | 60–90 °C (optimal range 70–90 °C) |
| pH range | 5.3–6.2 (optimal range 5.5–6.0) |
| Sealing time | Approximately 0.5–2 min/µm (typical value approximately 1 min/µm) |
| Air stirring | Weak air agitation recommended |
| Circulation filtration | Recommended, with acid-resistant and heat-resistant filter media |
| Tank material | Stainless steel SUS304 or SUS316 |
In the anodizing aluminum process, electrolytic colouring fills the base of each pore with metal — usually tin — and the tone you see comes from the way that deposit scatters light. Sealing then closes the pore above it. Get the seal wrong and the tone moves: the batch no longer matches the master panel that was signed off, and the difference shows in daylight rather than in the tank.
This sealer is built for that sequence. Applied to anodized aluminum after the colouring stage, it closes the film while holding the tone the colouring bath produced, so a bronze or a dark tone stays consistent from the first rack to the last. Colour is judged on a dry, sealed panel against a retained master; a wet film always reads darker and will mislead you.
Colouring and sealing are two halves of one result, so we supply both: a divalent tin salt electrolytic colouring additive for the stage before, and this sealer for the stage after. Specified together, the colour and the closure of the film are tuned against each other instead of being bought from two sources and matched afterwards.
Architectural aluminum. Window and door profiles, curtain wall sections and façade panels are judged outdoors, over years, and against each other. The sealing stage has to hold the colour the architect approved and keep the anodized aluminum weathering evenly, which is why a bath that drifts slowly and stays easy to control matters more here than a fast one.
Automotive trim and components. Exterior trim, roof rails and grille surrounds are bought against neutral salt spray results and against appearance on the vehicle. Parts that are electrolytically coloured or dyed go through the same seal, so the finish on a trim strip and the finish on a bracket can be held to one standard.
Consumer electronics and hardware. Housings, bezels and small machined parts are judged by hand and by eye: a smooth, closed surface, no marks from a permanent marker during inspection, and no fingerprints that will not wipe off. Sealing is the last wet step in metal finishing for those parts, so anything the bath leaves behind becomes a cosmetic reject.
Between them, these three sectors cover most of the work an aluminum anodizing service handles, and one bath serves all of them where the film specification is comparable. Where it is not — a 6 µm cosmetic film against a 25 µm exterior film — the difference is handled in dwell time and rack scheduling, not by buying a second sealer.
Phoenix Seal 149-T is used when sealing anodized aluminum and aluminum alloy parts, including parts that have been electrolytically colored or dyed. The right approach depends on the alloy in use and the sealing conditions on your line, so share those details with Fengfan to confirm how the product fits your parts and process.
Choosing the right match is where most sourcing decisions stall. As a trading supplier, we keep one point of contact from first enquiry to after-sales: tell us what you are making and the conditions you work under, and we shortlist the closest matches from our supplier network, compare specifications and arrange samples before you commit to a bulk order. If something does not behave as expected, we work with the supplying partner on the cause and a practical fix, and stay with the case until it is settled. Email, WeChat or WhatsApp enquiries get a reply within 24 hours.
Anodic films on anodized aluminum and aluminum alloys, whether the parts are clear, dyed or electrolytically coloured. That covers extruded profiles, machined and stamped components, trim and decorative housings — anywhere the film has to be closed after colour. The film specification, not the shape of the part, is what decides whether the product fits.
30–50 ml/L, with 35–45 ml/L as the preferred condition, and pH 5.3–6.2, targeted at 5.5–6.0. pH is the figure that moves first in production: carry-over on racks and parts from earlier stages of the anodizing aluminum process pushes it around, so it is checked daily and adjusted back into the window rather than corrected at the end of the week.
60–90 °C, with 70–90 °C as the preferred condition, and a dwell of approximately 0.5–2 min/µm of film, preferred at approximately 1 min/µm. In practice the time follows the film: a 10 µm film runs near ten minutes at the preferred condition, while a thin decorative film is through in a fraction of that. On an aluminum anodizing line the dwell is usually written into the route card per part rather than fixed once for the whole plant.
Weak air agitation is recommended — enough to keep temperature and concentration even across the tank, not enough to cool the surface layer or throw a foam head. Circulation filtration is also recommended, using acid-resistant and heat-resistant filter media. Filtration is what keeps particles out of the film; roughness or speckle on a sealed anodized coating is usually a filter problem before it is a chemistry problem.
Colour retention comes first: the sealed film holds its tone instead of bleeding dye into the rinse, the surface comes out smooth in the hand, it resists marking from a permanent marker, and the bath runs long enough that a production week does not end in a recharge. Salt spray performance at 70 °C is strong. A shop running an aluminum anodizing service normally qualifies on colour and salt spray together, against a retained master panel.
Stainless steel SUS304 or SUS316. Both grades are standard in metal finishing and stand up to a weakly acidic bath at sealing temperature. If your tank is anything else — a lined mild steel tank, for example — tell us before you charge it and we will say whether it is worth converting or replacing before the first production lot.
