In order to improve and beautify the surface condition of fiberglass products, increase the value of the product, and ensure that the inner layer of fiberglass is not corroded, and extend the service life of the product, we generally make the working surface of the product into a layer of adhesive with pigment paste (color paste) and high resin content. This layer of adhesive is called the adhesive coating layer (also known as the surface layer or decorative layer).
The quality of the production of the gel coat layer directly affects the external quality of the product, as well as its weather resistance, water resistance, and chemical resistance. Therefore, when spraying or brushing the gel coat layer, attention should be paid to the following points:
(1) When configuring gel coat resin, it is necessary to mix thoroughly, especially when using pigment paste. If the mixing is not uniform, it will cause spots and stripes on the surface of the product, which not only affects the appearance but also reduces its physical properties.
For this reason, mechanical stirring should be used as much as possible for mixing, and it is best to use a mixer that does not generate vortices to avoid mixing with air.
(2) Gel coats can be sprayed with a brush or a specialized spray gun. During spraying, 5-7% styrene should be added to adjust the viscosity of the resin and supplement the volatile loss of styrene during the spraying process.
(3) The thickness of the gel coat layer should be precisely controlled between 0.3-0.5mm, usually controlled by the mass of gel coat used per unit area, that is, the amount of gel coat used is 350-550g/㎡, so as to achieve the required thickness.
The thickness of the adhesive layer should be appropriate, not too thin, but also not too thick. If the adhesive layer is too thin, it may not cure completely, and the glass fiber on the back of the adhesive layer is easily exposed, affecting the appearance quality and not playing a role in beautifying and protecting fiberglass products.
If the gel coat is too thick, it is prone to cracking and is not resistant to impact, especially from the opposite direction of the product.
Uneven coating of the gel coat can also easily cause cracks during demolding, due to the uneven surface curing speed, which generates stress inside the resin.
(4) Gel coat should be applied evenly to avoid local accumulation as much as possible.
(5) The degree of curing of the adhesive layer must be well controlled.
The best way to check if the adhesive layer has solidified moderately is to use the touch method, which involves touching the surface of the adhesive layer with a clean finger. If it feels slightly sticky but not sticky to the hand, it indicates that the adhesive layer has basically solidified. At this time, the next step of pasting operation can be carried out to ensure the integrity of the adhesive layer and the backing layer.
Post time: Apr-07-2024
