PAP is propynol propoxylate, CAS 3973-17-9: a propoxylated propargyl alcohol supplied as a yellowish to yellow clear liquid at ≥85.0% assay by gas chromatography. It is well soluble in water, so it goes into a nickel bath as a simple water-based addition, and it stays stable in a closed drum between additions.
What it is used for
This is a top brightener and leveling agent for bright nickel plating — one building block in a brightener package, not a finished additive on its own. Formulators blend it with carriers, basic brighteners and other levelers to build a system; plating shops use it to top up a system they already run when brightness at the low-current end begins to fall away. Buying it as an intermediate rather than a ready-to-use product means you control the dilution, the ratio and the cost per active kilo.
How it behaves in the tank
In a working plating process the effect appears first where current density is lowest: recesses, the shadow side of a rack, the inner surfaces of a barrel load. Those are the areas that go dull or milky when the brightener is short, and they recover before the high-current areas change. That is why a Hull cell panel read from the low-current end tells you more about this component than a panel read at the centre.
Who buys it
Most of what leaves our warehouse goes to plating shops that run nickel plating services on steel, brass and zinc die castings, and to additive blenders who need a repeatable ≥85% grade for their own formulations. Both groups order the same drum; what changes is how tightly they specify the assay and how they handle lot traceability on site.
| Property | Value |
|---|---|
| Chemical name | Propynol propoxylate |
| Synonyms | Propargyl alcohol propoxylate; PAP |
| CAS No. | 3973-17-9 |
| Molecular formula | C6H10O2 |
| Molecular weight | 114.1 |
| Chemical class | Propoxylated acetylenic alcohol, nonionic |
| Physical form | Yellowish to yellow clear liquid |
| Concentration (GC) | ≥85.0% |
| pH | 2.5–6.5 |
| Density | 0.97–1.01 g/cm³ |
| Solubility | Well soluble in water |
Decorative nickel on steel and brass
Bright nickel plating over polished steel, brass and zinc die castings is the classic case: the deposit has to read white and mirror-bright before chrome goes on, and any haze in the nickel shows through the chrome. This grade is dosed into the nickel tank to hold that brightness across the rack load, including the parts hanging at the edges.
Job shops running nickel plating services
Shops that plate for several customers in a week see demand switch from mirror decorative work to satin and semi-bright. Because the effect sits at the low-current end, it responds well to small trims rather than a full re-make of the bath, which suits a job shop that cannot afford to drop a tank for a day.
Nickel as an underlayer in a metal plating process
Where nickel sits under chrome, under gold or under a decorative topcoat, leveling matters more than raw gloss — the smoother the nickel, the less polishing the finishing line has to do afterwards. Adding this component at the end of the brightener set is the usual way to buy that smoothness without changing the carrier system.
Multi-line operations
Where a nickel plating company runs rack and barrel lines on the same site, keep the two make-up records separate even when the drum is shared. Barrel work usually needs more frequent small additions because drag-out per load is higher relative to the bath volume, and mixing the records makes it impossible to see which line is drifting.
Alongside this grade, the same range covers the rest of a plating line. For acid zinc there is Fengfan Brightener for SZ-30B Sulfate Zinc Plating; for alkaline zinc, Fengfan Bright Zinc Alkaline for Rack and Barrel Plating ZN 50 and Fengfan Brightener for Cyanide Free Alkaline Zinc Plating ZN-500; for colouring after tin plating, Fengfan Phoenix EB 204A-204B Divalent Tin Salt Electrolytic Coloring Additive; for anodising, Fengfan Phoenix Seal 149-L Middle Temperature Sealing Agent for Aluminum Anodizing and Fengfan Phoenix Seal 149-T Medium Temperature Sealing Agent; for copper, Fengfan High Deposit Brightness Copper Plating FI-970 Bright Acid Copper Plating Process; for masonry and concrete, Fengfan Wood Stone Concrete Nano-Protective FF-4219; for nickel bath maintenance, Fengfan Nickel Purify P3; and for chrome lines, Fengfan Environmentally Friendly Chrome Mist Inhibitor FF-116. Ordering several items together keeps the documentation and the shipping schedule in one place, and our sales contact can tell you which of them share a packing format.
This grade is supplied in 25 kg drums. Keep the drum closed between additions and store it in a cool, dry, ventilated place out of direct sunlight; a water-soluble brightener does not benefit from being left open to humid air or to freeze–thaw cycles on a loading dock. Keep it away from strong oxidisers and concentrated acids, and never transfer it into an unmarked container — the label carries the lot number that ties the drum to its inspection certificate. Use a clean, dry drum pump or dipper reserved for brightener components so that water or nickel drag-out does not get back into the drum. If a drum has been open across a long season, draw a small sample and compare it with a fresh reference before dosing a production tank; appearance and assay should still match the table above. A full drum is heavy, so plan a trolley or a fixed pump position rather than lifting it onto the tank edge.
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.
They are different molecules, not different dilutions. This one is propoxylated, C6H10O2 with a molecular weight of 114.1; the ethoxylated grades carry a shorter chain and a different solubility and brightness profile. In practice both serve as top brighteners in bright nickel plating at low addition levels, and the choice comes down to how much leveling you want against how much brightness, and to what your carrier system already contributes. Compare them on a Hull cell panel rather than on price per drum.
Yes. In electro nickel plating the same component works in both, and what changes is the rhythm rather than the chemistry. Barrel loads drag out more solution per kilo of work, so additions come more often and in smaller amounts; rack work with large parts tends to need fewer, slightly larger corrections. Keep a separate make-up record for each line so a drift on one cannot be mistaken for a change on the other.
The brightener does not choose the substrate — the preparation does. On steel, the nickel goes straight onto a well-cleaned, activated surface; on zinc die castings it normally sits over a copper strike, and brightness problems there usually trace back to the strike or to zinc contamination rather than to the brightener. If a panel is dull only on one substrate, check the pre-treatment sequence before changing the nickel plating addition.
The product itself is acidic, so a large correction can move a bath that is already running near the top of its window. In a stable plating process the shift from a normal addition is small, but check with a meter rather than pH paper and correct before the next load. A bath that needs pH correction after every brightener addition is usually telling you the addition is too large for the tank volume.
Read both ends. A dull or milky low-current end with a still-bright high-current end supports a short brightener, so a small addition is the right move. Haze or a brittle-looking deposit across the middle of the panel, with brightness at the edges, points the other way: the metal plating process has more brightener than it can hold, and the answer is dilution or a partial bath change, not another addition.
Shops offering nickel plating services usually keep one bath and trim it per job rather than keeping two. Decorative work is run at the brighter end of the window; satin and semi-bright jobs are run lower, sometimes with the carrier adjusted instead. The practical rule is to move in small steps and record the panel result for each customer's job, so the next run starts from a known setting instead of from guesswork.
