Views: 2 Author: Site Editor Publish Time: 2019-01-25 Origin: Site
Shade net, also known as shading net, plays a very active and useful role in vegetable cultivation and pest prevention in summer. Many people have a question: Why is sunscreen black and white not more reflective?
Black net is suitable for vegetable production with weak light demand, while white net is suitable for photophilic vegetable production. Black net is suitable for short-term cover-up, while white net is suitable for full-growth cover-up.
The shade net manufacturers should strictly expose and cover the black net according to different vegetable and vegetable growing period, while the white net is not strict. It is not necessary to uncover the net before seedling emergence, but it is necessary to pay attention to uncovering the net in time after seedling emergence. Floating cover can also be used after transplanting and planting, but it should be exposed day and night.
First of all, please note that it's sunscreen, not sunscreen pad. Sunscreen mats are usually made of reflective tin paper. They are usually used on the cushions of bicycles or motorcycles. This cushion is airtight and has a high production cost. Of course, its reflective effect is the best.
Second, pay attention to the word "net". That is to say, to ventilate, once the area is large, if not ventilated, it will be more stuffy. But why not a white web? If it is white and ventilated, it will reflect light around, and inside is no exception. You can do a simple experiment, assuming that there are black mosquito nets and white mosquito nets, the same aperture size, placed in the sun, is it white cool or black cool? The answer, of course, is black. Because it absorbs all the heat, while white does not absorb, it reflects directly. After the black net absorbs heat, it is easy to have small ecological wind because of ventilation, or even more because of the temperature difference between the black net and the surrounding environment.
Finally, there is also a cost problem, sunscreen is generally made of polyethylene, that is, petroleum refining residue. If you want white, it needs to be bleached, but it is not so easy to bleach, which will inevitably increase the cost.