Phoenix EB 204A-204B is a two-component divalent tin salt additive built for the electrolytic coloring stage of the anodizing aluminum process. It is not a dye and it is not a sealer: it works on a surface that already carries its anodic oxide film, and it colors that film by depositing tin from a stannous sulfate bath into the pores of the oxide layer, ahead of sealing.
The set is supplied as two liquids because the two jobs are different. EB204A and EB204B are made up and replenished separately, so the bath can be trimmed toward the color you are running instead of being pushed around by one blended product. EB204B carries a high stannous sulfate content together with special additives, and that concentration is what holds the bath steady across a production shift.
The working bath is a sulfuric acid system running close to room temperature, without air agitation, and it settles down quickly once the tank is lined out.
Typical users are plants that anodize aluminum for architectural profiles and panels, automotive trim and structural parts, and electronics or decorative components, together with the distributors who keep those plants supplied. Settings for your own line depend on the alloy, the anodic film, the color you need and how the tank is arranged, so treat the figures on this product as the working window and fine-tune inside it.
| Parameter | Setting |
|---|---|
| Product model | Phoenix EB 204A-204B |
| Product type | Divalent tin salt electrolytic coloring additive |
| Main component | EB204B solution with a high stannous sulfate content |
| Application | Electrolytic coloring of anodized aluminum and aluminum alloy parts |
| Sulfuric acid (H2SO4) | 18–22 g/L operating range; 20–22 g/L optimum |
| Phoenix EB204A | 20–40 g/L operating range; 25–35 g/L optimum |
| Phoenix EB204B | 76–116 g/L operating range; 90–100 g/L optimum |
| Temperature | 21–23 °C operating range; 20–22 °C optimum |
| Processing time | approximately 0.5–20 min operating range; 5–15 min optimum |
| Air stirring | not recommended; not used under optimum conditions |
| Circulation filtration | recommended; used under optimum conditions |
| Storage note | a small amount of precipitate may appear during long-term storage because of the high stannous sulfate content; this does not affect use |
Automotive anodizing is unforgiving about color. Trim strips, roof rails, mouldings, brackets and extruded sections often end up on the same vehicle, sometimes from different production runs, and a step that varies between batches is visible from three metres away. That is the job this additive set is aimed at: an anodized aluminum component finished to the same tone as the one beside it.
Complex geometry is where the bath earns its place. Extruded profiles and pressed parts carry recesses, tight radii and shadowed faces where a weak coloring bath shows itself immediately as a pale patch. Good distribution keeps those areas closer to the flat faces, which cuts the re-racking and touch-up that eats into output.
Automotive programs also run for years, with service parts pulled long after launch. A line that can anodize aluminum to the same setting run after run is what makes a replacement batch match the original. Acid, both components, temperature and time inside the window, filtration running — the next run starts where the last one finished.
Small parts are a different problem from long extrusions. Housings, bezels, control-panel fronts, decorative trim and the many small aluminum components that end up inside electronic assemblies are usually racked densely, and the aluminum anodizing process feeding that rack has to reach every part the same way. A bath with poor distribution shows itself here as a gradient across the load rather than one bad component.
Even color distribution is what does the work. Because the two components are controlled separately, a bath that has been running a dark tone can be brought back for a lighter one without a full dump and rebuild.
Decorative work also has a habit of coming back. A customer approves a sample, orders again six months later, and expects the same finish. The repeatability of a stable bath — same acid, same additions, same time, filtration running — is what makes that second order match the first.
Where the parts are functional rather than decorative, the coloring stage still has to be predictable, because it sits between the anodizing tank and sealing and any variation carries through both.
EB204B is the concentrated half of the pair, and it is the one that needs care in the store. IBCs and drums should sit under cover, out of direct sunlight, in a cool and dry area, with the bungs closed between draws.
Before drawing an addition, roll the drum or recirculate the contents. A concentrated stannous sulfate solution can settle a little over time, and an addition pulled off the top of a still drum is not the same as one pulled from a mixed drum. That single habit is what keeps dosing honest.
Rotate stock so the oldest drum goes first, and keep EB204A and EB204B in their own labelled containers. Blending them ahead of time throws away the separate adjustment the two-component system exists to provide.
If a delivery arrives looking different from the one before it, talk to us before you charge it to the tank. A photograph and the batch number are usually enough for us to tell you whether you are looking at normal settling or something that deserves a second look.
The right use scenario for Phoenix EB 204A-204B divalent tin salt electrolytic coloring additive is determined by your aluminum alloy, required color, bath volume and production conditions. Fengfan can review those variables with you to match the additive and process support to your line.
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.
It is designed for electrolytic coloring on anodized aluminum and aluminum alloy parts — the anodic film has to be there first, because that film is what takes the color. Within that, it handles flat panels and the harder cases equally: complex surfaces, deep recesses, and racks carrying parts of different geometry. Bare aluminum is not the substrate for this stage, and sealing happens afterwards.
Work to 25–35 g/L of EB204A and 90–100 g/L of EB204B. The full operating ranges are 20–40 g/L and 76–116 g/L, so there is room to trim if the color or the bath calls for it. Set the sulfuric acid to 20–22 g/L (range 18–22 g/L) first, because both components behave differently against an acid figure that has drifted.
No. Air stirring is not recommended and it is not used under the optimum conditions. Circulation filtration is what the anodizing aluminum process asks for instead — the bath keeps moving and stays clear without air being pushed through it.
20–22 °C is the optimum band and 21–23 °C is the working range. The run is typically 5–15 minutes, with the full window stretching from about 0.5 minutes to 20 minutes. Because the temperature sits close to ambient, most of the control you have over color depth comes from how long the parts stay in the bath.
No, it does not affect use. EB204B is deliberately high in stannous sulfate, and a small amount of precipitate can appear during long-term storage as a result. Mix or recirculate the drum before drawing an addition so the dose you take represents the whole contents.
Because one blended product only lets you move everything at once. EB204A and EB204B do different jobs in the bath, so dosing them separately means you can shift the bath toward the color you are running without overcorrecting the other side of it — and every addition becomes a number you chose and can record.
Good color distribution is the reason this system suits awkward geometry, and it is what buyers anodizing aluminum in mixed racks notice first. Color reaches into recesses and around corners, so a rack of different shapes finishes closer to even. It does not override racking, though: parts that shield each other will still shield each other.
Go back to the acid first. Free acid outside 18–22 g/L changes how both components behave, and correcting the components before the acid usually makes the drift worse. Then confirm that filtration has genuinely been running, and pull a coupon before committing a full load. If the color still will not come back, send us the additions you made and the coupon result.
