
We have received an inquiry about faint spots that are visible through the fabric of a nap blanket.
Our nap blankets are made from plain fabric, so dark dots may be visible on the inside.
We often receive inquiries from customers asking, "Are those black spots mold?" However, they are not mold.
●What are the black spots?
These spots are most commonly seen when using 100% cotton filling.
As its name suggests, cotton plants bloom as flowers and then bear fruit. In the fall, the fruit splits open to reveal white fluff.
This fluff is extremely soft and makes an ideal filling for duvets.
However, when collecting the fluff, it is inevitable that small pieces of stems and leaf sepals (the parts that support the flowers) will get mixed in. These are the dark spots you may see on the inside of your futon.

Before being made into products, the harvested cotton is "refined" by machine to remove as many impurities as possible, such as leaves and stems. However, it is technically difficult to remove all of these impurities 100%, and very small amounts remain in the cotton.
These impurities can easily show through, especially if you use plain white or off-white fabric, like the fabric used in our nap blankets.
(On the other hand, on colorful, printed fabrics, these tiny specks are usually much less noticeable.)
Even Indian and Mexican cotton, which are highly valued around the world, is not uncommon to have small black spots scattered throughout, which are characteristic of natural materials.
These spots that may be found on a new cotton-filled duvet are due to the natural characteristics of cotton and do not pose any quality issues when used, so you can use it with confidence.
However, if you notice new black spots on the surface or outside of your futon after repeated use, it is possible that these are "black mold."
Mold can be a health hazard, so you should be careful in such cases, and we recommend cleaning and proper care if you find it.
● Still the most popular filling is "100% cotton" ●
The filling of the nap blankets we offer comes in four types: 100% cotton, blended cotton, anti-mite polyester, and recycled cotton.
You can choose the filling according to your child's constitution, but "100% cotton" is the most popular choice among many customers.
<Characteristics of 100% cotton>
- Made from natural materials, it has excellent moisture absorption and dissipation properties
・Excellent sleeping comfort
- Easier to crush than other cotton
Every material has its advantages and disadvantages.
The best things about 100% cotton are that it is comfortable to sleep on and is a comfortable material with excellent moisture absorption and dissipation properties.
Made from 100% natural cotton, it is free from the uncomfortable, restless sleep that is typical of synthetic fibers.
Children can also sleep soundly and stress-free.
We have tried to explain as clearly as possible about the black spots visible in the fabric.
I can fully understand your feelings of anxiety.
It's not a very pleasant feeling to see something faintly black peeking through the fabric.
Because it is a natural material, we are concerned that there can be years when there are a lot of cotton husks, depending on the crop yield and harvesting method.
However, we feel that it is very worthwhile to choose a material that can effectively absorb and release moisture for the filling of the nap blanket that your child uses every day.