Pickling Gel vs. Paste vs. Liquid: Which Derustit Product to Use
Bradford Derustit makes several stainless steel treatments, and the first question most buyers have is simple: which one do I need? The answer usually comes down to two things — the form factor (does the chemical need to cling to a weld, or can you immerse a part?) and the job (are you removing weld heat tint and scale, restoring corrosion resistance, or just brightening a surface?). This guide walks the whole line, explains what each product does and doesn’t do, and matches common jobs to the right product. We’ve been manufacturing these chemistries in the USA for over 50 years, so the distinctions below are the ones that actually matter on the shop floor.
Form factor first: gel, paste, and liquid
Before you pick a product, understand the three physical forms — because form decides how and where you can apply it.
- Gel (Wonder Gel) — a thick, clinging gel you brush on. It stays put on welds, vertical surfaces, overhead seams, and complex geometry that a dip tank can’t reach. No electricity, no immersion equipment.
- Paste (Derustit SS-3 Paste) — even thicker than a gel, built to cling to a specific weld seam or heat-affected spot for targeted treatment.
- Liquid (Derustit SS-3 Liquid) — a pourable solution ideal for immersion, spray, or wiping down larger clean surfaces. Where you can submerge a part or treat a broad flat area, a liquid is faster and more uniform than brushing.
Rule of thumb: if gravity is working against you — a vertical weld, an overhead joint, a corner — reach for a clinging gel or paste. If you can immerse the part or lay the surface flat, a liquid covers more ground with less labor.
Job first: pickle, passivate, or just brighten?
Form factor narrows the field, but the job decides the product. Three terms get used loosely, so keep them straight:
- Pickling removes a layer of the surface — weld heat tint, oxide scale, and the chromium-depleted zone left by welding. It’s aggressive and intentionally takes off a little base metal where there’s scale to eliminate.
- Passivation is milder: it dissolves free iron and contaminants so the steel’s protective chromium-oxide film re-forms. It does not remove heat tint or scale, and it removes essentially no base metal.
- Cleaning & brightening is lighter-duty still — lifting light rust, heat stains, water spots, and oxidation to restore appearance. It is not descaling and not full passivation.
For the full breakdown, see Pickling vs. Passivation. The short version: a welded part with heat tint needs pickling (and ideally passivation in the same step); a clean, machined part needs passivation; a surface that merely looks dull or spotted needs brightening. Don’t ask a brightener to do a pickler’s work — it won’t touch heavy heat tint or scale.
The product-selection table
This is the heart of the decision. Find your job in the “best for” column and the form that fits your part.
| Product | Form | Removes heat tint & scale? | Passivates? | Best for | Typical use |
|---|---|---|---|---|---|
| Wonder Gel | Gel (brush-on) | Yes | Yes | Welds, vertical & complex geometry needing pickle + passivate in one step | Brush on the weld/heat-affected zone, dwell ~10–15 min, rinse |
| SS-3 Liquid | Liquid | No (passivation-focused) | Yes | Passivating clean, machined, or fabricated parts; immersion & larger surfaces | Immerse, spray, or wipe down, then rinse |
| SS-3 Paste | Paste (brush-on) | Yes | Yes | Spot-treating individual welds & heat-affected seams | Brush onto the weld, dwell, rinse |
| B-P No.1 Brightner | Liquid | No (light duty) | No | Light rust, heat stains, water spots, oxidation — brighten & clean | Apply, let it work, rinse; finishing & maintenance |
| B-P Metal Cleaner | Liquid | No (light duty) | No | General metal cleaning — surface rust & oxide removal | Routine cleanup & maintenance, then rinse |
| Passivation Test Kit | Copper sulfate reagent | n/a (verification) | n/a (verification) | Confirming a surface is free of free iron after treatment | Apply to clean, dry metal; a pink copper deposit means free iron remains |
Which product? A decision flow
Walk the questions top to bottom and stop at the first match.
Matching common jobs to products
Welded part with heat tint → Wonder Gel or SS-3 Paste
Heat tint marks a chromium-depleted zone, so the surface must be pickled, not just passivated. Both Wonder Gel and SS-3 Paste remove heat tint and scale and restore the passive film in one brush-on step. Choose Wonder Gel for runs of welds, vertical seams, or complex geometry; choose SS-3 Paste when you’re spot-treating an individual weld. See how to remove heat tint and how to passivate welds.
Clean or machined part → SS-3 Liquid
If there’s no scale or heat tint — just free iron from tooling and handling — you only need passivation. SS-3 Liquid is built for this, and its pourable form makes immersion or wiping down larger surfaces straightforward. Our complete passivation guide covers the process end to end.
Dull, spotted, or lightly rusted surface → Brightner
When stainless just looks tired — water spots, light surface rust, heat stains, oxidation — and there’s no scale to descale, B-P No.1 Brightner cleans and brightens it back to a uniform finish. It’s a finishing and maintenance product, not a descaler.
Routine metal cleanup → Metal Cleaner
For everyday rust and oxide removal where you don’t need passivation, B-P Metal Cleaner is the lighter-duty, general-purpose choice.
Verifying the result → Passivation Test Kit
After any pickling or passivation step, confirm it worked. The Passivation Test Kit uses the copper sulfate test: free iron plates out a pink copper deposit, while a properly passivated surface shows none — the on-the-spot check for ASTM A967 / A380 acceptance.
How these fit the standards
The pickling and passivation products are formulated to help parts meet ASTM A380 (cleaning and descaling) and ASTM A967 (chemical passivation). Wonder Gel, SS-3 Liquid, and SS-3 Paste are all used to meet those practices; the Passivation Test Kit verifies the free-iron acceptance criteria. Wonder Gel (NSF registration #148253) and SS-3 (#148254) are also NSF Nonfood Compounds registered (Category A3), which matters for food, dairy, and pharmaceutical equipment.
Chemistry choice is a related decision — see citric vs. nitric vs. pickling and electropolishing vs. pickling for how these fluoride-based pickling gels compare to other approaches.