Why Pearl Plastic Parts Show Flow Marks?

Pearl-colored foam pumps often exhibit flow marks (flow lines) because of how the pearl pigment works. The pigment is heavier and thicker than normal colors, so it doesn't mix as evenly when the plastic flows.

Where Do Flow Marks Usually Appear?

1. Weld Lines (Molding Lines)

When melted plastic flows from two directions and meets, the pearl pigment can clump there, making a visible line. Please see the picture below.

2. Near the Injection Point (Gate) 

The high pressure at the gate can push the pigment unevenly, causing streaks or marks.
 

Are Flow Marks Normal?

Yes, flow marks are common with pearl colors and are usually acceptable in the industry. However, it's best to check with your customer to ensure they're okay with this.

If flow marks are a problem, another option is pearl-color overspray (painting the part after molding). This avoids flow marks but costs more.

Specialized Foam Pump Supplier

As a specialized foam pump & bottle supplier, PartnerPkg offers foam pumps/bottles with a wide range of custom options, premium quality, and factory-direct pricing. We serve cosmetic packaging distributors, OEM/contract manufacturers, and brand owners all over the world. Free samples are offered. Response in 24 hours.

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