Folding 1. Types of Folding

Folding is a cross section finishing method that covers the leather section with thin leather.
It is called as Rimbocco in Italian.
It is to fold an extra piece of leather and to put it inside like the meaning of ‘folding and attaching’.
At this time, the folded leather should be thin enough to fold well. For this, we already learned about skiving that cut the leather with certain thickness.
But if the leather is too thin, durability will be a problem and leather can be torn or pierced easily.
For the folding, you’d better to cut the leather with extra 0.8cm and skive with 1.2cm of width and 0.5T (T is a unit of thickness, 1T is 1mm) of thickness.
To have a good outcome of folding, the preceding skiving should be done well, and the good folding also affects the machine. In other words, you can see the precise degree of the work process and quality of bag by seeing how neatly it is folded.
Folding can be divided into the followings.
1) Straight folding
2) Perpendicular folding (Interior angle, exterior angle)
3) curved surface folding (Interior angle, exterior angle)
Straight folding is to cover the entire line with leather.
You can fold along the straight line after bonding the extra leather part.
At this time, it is important to make the surface to be folded straight.
If the end of the straight line is perpendicular, perpendicular folding is done.
Processing method can be different depending on the interior angle and exterior angle.
Let’s take a look the exterior angle with the photo.

As shown in the photo, cut the diagonal line of point where two straight lines intersect.
At this time, you need to think about two things.
When you cut it diagonally, cut it with space than right angle end, not cutting too much at a time.

So, you have to check that the two sides are stacked up without overlapping when folding like the photo. You also have to check whether the stiffeners are all wrapped if there is a stiffener inside.
If you cut the leather too much, it can’t cover all of the cross section and inside can be seen. So, you’d better to cut by dividing into two or three times.
And the cut surface should be slightly slanted outward, not being perpendicular.
Since the two surfaces are overlapped like the above photo, joint part can be attached more naturally without any boundaries if two leathers attached to the slanted surface rather than attaching two leathers at right angles.
This is the same as the reason for hand skiving when two leathers overlap.

In case of rectangle as shown in the photo, you can cut the entire square diagonally.
When the bonding is dried to some extent, you can fold the part to be folded with Stecca (tool for folding — and fold each surface).

Then, folding is completed as shown in the photo.
Next, let’s look at how to fold curved surface.
There are interior angle and exterior angle.
We will see the exterior angle first.

The important thing on the curved surface is that the skiving should be thinner than the straight line so that folding could be done well.
This is because there are many overlapping areas of leather when folded after bonding according to round.
So, it is good to skive with hand again in the curved surface separately after machine skiving.

When building the leather after boding, the leather will be curved like the photo.
This curved surface will overlap each other.

This is view seen from the outside. It is important to make a clean shape on the curved surface especially when it is folded.
It is a little more difficult than straight line.
To do that, accurate round should be made when cutting the inside stiffener.
Then, when you fold, you need to pull the leather inside to make better curved surface.
Of course, relatively stretchy leather will have a better curve along the stiffener, but on the contract, the less elastic leather will be harder to make better curve, so you need to be more careful.
Folding in curved surface is one of the most difficult folding.

Pull out the leather from outside to inside with awl as shown in the photo.
In this way, leather could stick to the stiffener.

You need to pull the leather based on the center of round, drag the half of center and then drag other half of the center to make as few wrinkles as possible.

For the curved surface, there may be overlapping of the leather like the photo.
At this time, you should remove the raised part.
The reason is that when the matching stitching is done later, the thickness of the leather should be even and uniform. Otherwise, the needle may bounce.

If you finish at this point, you should be careful not to hurt parts of the leather visible from the outside.
It is very likely to happen if the blade of knife is long. In this case, it will be helpful to use smaller knife like the photo.

Curved surface folding is completed.
Since it takes a lot of time for edge coat to be applied, folding is used a lot for the bag production. Unlike edge coat, partial skiving machine should be equipped for the folding. If the lines are complex, folding would be more difficult than the edge coat.
The outcome of folding that looks neat is also very attractive as the edge coat that shines like glass.
Which one do you like more among edge coat and folding?
