Pretreatment for Paint

This is the comprehensive "Pre-Paint Surface Treatment Masterplan" for Zinc Alloy.

The Golden Rule of Painting: "Paint is 80% Preparation."

If you paint directly onto raw die-cast zinc, it will peel. Zinc naturally forms a loose oxide layer ("White Rust") that prevents adhesion. You must remove this and replace it with a chemical "anchor" (Conversion Coating).

This plan is sized for 500 KG / Day (Approx. 50,000 zipper pulls/buttons) using the [QLQ System].

🛡️ Zinc Alloy Pre-Paint Treatment Masterplan (QLQ System)

Objective: Create a Class 0 Adhesion surface (Cross-Cut Tape Test Pass).

Method: Ultrasonic Dewaxing + Nano-Ceramic Conversion Coating (ZAP).

Capacity: 500 KG/Day (1 Shift, 10 Hours).

Process Type: Semi-Automatic Ultrasonic Line (Basket System).

Part I: Equipment Configuration (The Hardware)

To handle 500kg efficiently, you cannot use buckets. You need a linear tank line.

Ultrasonic Cleaning Line (5-Stage):
- Tank Dimensions: $600 \times 600 \times 600$ mm (Approx. 200 Liters).
- Material: SUS304 Stainless Steel (Heated).
- Ultrasonic Power: 1500W – 2000W per tank (28kHz or 40kHz).
- Filtration: Oil skimmer and circulating pump on Tank 1.
Drying Oven (Tunnel or Cabinet):
- Type: Air Circulation Batch Oven or Mesh Belt Tunnel.
- Temp: Capable of 150°C.
- Inner Material: Stainless Steel (to prevent rust dust).
Water System:
- RO Pure Water Machine: 500L/Hour. (Final rinse must be pure to prevent salt spots).
Baskets:
- Type: Stainless Steel Mesh Baskets ( $400 \times 400$ mm).
- Load: ~10-15 KG per basket.

Part II: The Chemical List (QLQ System)

Sourcing: [QLQ Product] for performance; [Purchase Locally] for acids.

Chemical Name	Function	Consumption Est. (Per Day)
1. [QLQ] Liquid Wax Remover	Dissolves Polishing Wax	2 – 3 Liters
2. [QLQ] Ultrasonic Degreaser	Removes Oil/Dirt	1 – 2 KG
3. [QLQ] Zinc Activator (Acid)	Removes Oxide Skin	0.5 – 1 KG
4. [QLQ] Nano-Ceramic ZAP	Adhesion Promoter (Conversion)	1 – 1.5 Liters
5. [Purchase Locally] Sulfuric Acid	pH Adjustment	Minimal

Part III: The Process Workflow (SOP) & Time Study

Throughput Calculation:

Total Target: 500 KG.
Batch Size: 15 KG / Basket.
Total Batches: ~34 Batches per day.
Cycle Time: 1 Batch every 15-18 minutes.

Step	Process Name	Temp	Time	Chemical / Formula	Purpose
1	Hot Dewaxing (US)	70-80°C	5-8 mins	[QLQ] Wax Remover (3-5%)	Melts heavy polishing wax from logos/holes.
2	Fine Degreasing (US)	60-70°C	3-5 mins	[QLQ] Degreaser (30 g/L)	Removes oil film. Makes surface hydrophilic.
3	Flowing Rinse	RT	1 min	Tap Water	Removes alkali residue.
4	Surface Activation	RT	30-60 sec	[QLQ] Zinc Activator (1-2%)	Slightly etches the zinc skin. Removes oxidation. Crucial.
5	Flowing Rinse	RT	1 min	Tap Water	Stop acid reaction.
6	Nano-Ceramic Conversion	RT - 35°C	1-2 mins	[QLQ] Nano-ZAP (3-5%)	Creates a colorless, nano-scale "glue" layer. Replaces Phosphate.
7	Pure Water Rinse	40-50°C	1 min	RO Water (Conductivity <10µS)	Prevents water spots/stains under paint.
8	Dehydration Baking	120°C	20-30 mins	Hot Air	100% Bone Dry. Drives out moisture from pores.

Part IV: Personnel Configuration

Total Staff: 2 - 3 People

Line Operator (1 Person):
- Responsibilities: Loading/Unloading baskets, operating the hoist (or manual transfer), checking temperature.
Chemical/Maintenance Tech (0.5 - 1 Person):
- Responsibilities: Dosing chemicals, checking pH, skimming oil, maintaining the Ultrasonic generator.
QC & Staging (1 Person):
- Responsibilities: Inspecting dried parts (Water Break Test), packing into clean trays for the Spray Room.

Part V: Master’s Precautions (The "Don't Fail" Rules)

1. The "Water Break" Test (Every 2 Hours)

Before the parts go into Step 6 (ZAP), lift a basket out of the rinse.
Pass: Water covers the zipper pull completely like a sheet.
Fail: Water beads up (like rain on a waxed car).
Action: If it fails, add more [QLQ] Degreaser or change the water in Tank 1. If you paint over oil, it peels 100%.

2. The "Touch of Death"

After Step 2, NO BARE HANDS.
Human skin has oil and salt. A fingerprint on a Zinc Alloy part will appear as a "Rust Fingerprint" under the clear lacquer 3 months later.
Rule: Operators must wear clean cotton or nitrile gloves.

3. Drying Temp Control

Do not exceed 150°C in the drying oven.
Why? Zinc Alloy crystal structure changes > 150°C (aging), and the conversion coating might degrade. 120°C is the sweet spot.

4. The "4-Hour" Time Limit

Once parts are treated and dried, they are "Active."
Rule: You must paint them within 4 hours. If they sit overnight (especially in humid weather), the zinc will re-oxidize, and the ZAP coating will absorb moisture. The paint will bubble.

Part VI: Daily Output Schedule (Example)

08:00: Turn on heaters (Tanks take 45 mins to heat up).
08:45: Chemical Check (pH and Concentration).
09:00: First Basket In.
09:20: First Basket Out (Dry). QC Check.
... Continuous Cycle ...
12:00: Lunch (Cover tanks to save heat/water).
17:00: Last Basket In.
17:30: Turn off Heaters. Skim Oil.
Total Output: ~510 KG.

🌟 Featured Album: The "Adhesion Anchor" Series

Description for the Blog/Guide Album:

⚓ The "Adhesion Anchor" Album: Why Paint Peels from Zinc (And How to Stop It)

Painting Zinc Alloy without Pre-treatment is like painting on glass with grease—it just slides off. This album teaches you the Chemical Architecture of a perfect bond.

What you will learn:

🧪 Nano-Ceramic vs. Phosphate: Why the old-school heavy phosphate sludge is dead. We introduce [QLQ Nano-ZAP], the invisible coating that increases paint grip by 300%.
🧼 The "Invisible Wax" Killer: Polishing wax hides in the text of your zipper logo. Learn how to tune your Ultrasonic Frequency to blast it out before it ruins your paint.
🔥 The Pre-Bake Secret: How drying your parts at the wrong temperature causes "Blistering" inside the paint oven later.
✋ The Glove Protocol: Why a single fingerprint on a pre-treated buckle is a $5.00 loss, and how to handle parts safely.