Jeremy Rubin's Blog

Here you'll find an assorted mix of content from yours truly. I post about a lot of things, but primarily Bitcoin.

categories: Bitcoin, Shenzhen Journey.

Leather Factory Tour

Shenzhen Adventure Day 17

Today we visited the PrimeAsia Leather Factory.

Welcome to PrimeAsia A warm welcome.

A ‘real’ welcome.

The leather comes in to the factory pre-treated. The tannery is (typically) these days co-located with the slaughterhouse. At the tannery they chrome treat the raw leather and then put it in a shipping container to wherever it is going.

Pile of raw leather “wet blues”, waiting to be processed

Quality Inspection

The leather is then cut through the middle (ie, reducing the thickness) to a top-grain piece and a suede piece.

The suede leather is then buffed down to standardize thickness. (the top-grain needs no buffing as it is cut to the right size).

The leather dust is then captured and put into random products, like asphalt.

Leather dust

The leathers are then dyed in these big tumblers. They can do any color – they mix chemicals on site.

Oh that tumbler was just a baby, for color testing and sample runs. No. This is a tumbler:

Look at the people to get a sense of scale

The dyed leather comes off the line

Post Processing

There’s a myriad of leather post processing steps depending on the finished product.

You can turn a cow into a crocodile:

This is done by melting a plastic sheet into the leather.

You can embed thermal-color change wax:

Bright pink dyed and super soft suede:



A really cool section was the testing facilities. This ensures the quality of the finished product.

There are machines that can test the rigidity, flexibility, waterproofness, etc.

Water Purification

Leather is notorious for pollution. At PrimeAsia, they have a big and fancy water purification plant on-site.

We start our tour from the control panel

Water starts out a bit frothy (I believe it’s a bacterial processing phase)

Water is cleaner!

Clean water comes out here.


Leather is cheaper than I thought. It was maybe $100 for a whole pelt.

There’s no natural leather color. After chrome tanning, all leather is blue-gray.

Shenzhen Maker Faire

Shenzhen Adventure Day 14

We were lucky enough to overlap our stay with the Shenzhen Maker Faire!

Panorama of  the faire

Panorama of  the faire

There were a lot of drones…

Drones! Drones everywhere

I even ran into some friends!

Lizhou Sha MIT ‘18

Deb Weinswig, my cousin!

We finished off the day at the Hackaday pizza party.

What struck me most is that we were like an hour out of the city by subway but it still looked like this:


The amount of construction in the region is insane.

How is Shenzhen so green?

Shenzhen Adventure Day 13

Watering trucks! Saw this during a night out. They go around and spray down all the fancy greenery.

Engineering Query at King Kredie

Shenzhen Adventure Day 12

Inside the King Kredie Engineering Query room

On Day 9 I mentioned that we had submitted our boards for Engineering Queries, but I didn’t quite explain what those are.

When you’re working with a good manufacturer, they don’t just blindly produce what you tell them, they will go through and verify certain properties of the design to make sure it will come out as expected, or even tell you ways you can save costs that you may not have thought of. This is because:

  1. they want your future business
  2. they’re just good people
  3. they don’t make more money on the more expensive process

3 can happen because a different process may have no different labor cost, but just a material cost which they don’t mark up. This is an important point to keep in mind when working with various manufacturers – they will pass savings on to you if possible!

Flex PCB Factory Tour at King Kredie

Shenzhen Adventure Day 12

While we were doing the Engineering Query at King Kredie, we also got a special bonus tour: Flex PCB Manufacturing.

Flex PCB is kind of the future – as devices get smaller, a thick-old-green PCB is no longer practical unless it is also a structural element. Flex PCB’s, traditionally used more often as a custom connector, can be populated with components as well so are a really cool technique to experiment with.

The process is pretty different from traditional PCB etching.

You start with a big roll of copper foil.

Punch out a pattern using a big press.

The die looks like this:

Then you laminate it. The laminate sheet has also been punch cut appropriately.

An iron is used to bond the plastic laminate to the copper/backing laminate.

Then you (optionally) silkscreen print on

Alignment is not critical here.

Finished product:

This flexpcb has a stiff copper trace inside of it as well for rigidity on that axis

Later on, these will need to be cut out/depanelized.

© 2011-2021 Jeremy Rubin. All rights reserved.