Gel coat is an unsaturated polyester coating that gives reinforced plastic products protection and gives the outer layer a lasting desired color. Improper use of gel coat may result in a series of problems. The following is a simple analysis of some common problems.
1. Sagging, the reason may be that the viscosity of the gel coat is too low; the gel coat is too much, the gel coat is too thick; the technical reasons for spraying; the nozzle is too small or the angle is inappropriate; the spray pressure is too high or the spray gun is not close to the mold; the mold Cause of release agent; gel is too slow.
2. Fisheyes may be caused by static electricity on the surface of the mold; the mold release agent is wrong; the mold is dirty or dusty; the gel coat layer is too thin; water, oil or grease pollution; there are wax aggregates on the mold; gel coat temperature Too low.
3. Peeling, the cause may be that the gel coat is too thick or uneven; the dosage of the catalyst is too high; the gel time of the gel coat is too long; the cause of the release agent; the cure of the gel coat is uneven; the reinforcement layer resin is too much or the cure is too low ; Inhibition of styrene leads to uneven curing.
4. Wrinkles may be caused by the gel coat being too thin or uneven; the temperature is too low or the gel coat is cold; the humidity is too high; too much spray; too much or too little catalyst; the upper reinforcement layer is too early; pollution.
5. Trachoma may be caused by too much catalyst or the surface of the mold is covered with curing agent; the spray pressure is too high or the atomization is not good; the mixing is too strong when mixing the catalyst; the gel coat is too thick.
6. The resin/pigment separation may be caused by too close spraying distance or high pressure; the nozzle is too large; the spraying technology is wrong (turbulent); the gel coat is too thick (sagging).
7. The exposed fiber may be caused by: the gel coat is too thin; the gel coat is not cured; the upper reinforcement layer is too early; the glass fiber is rolled too heavy; the resin exotherm is too high; and the mold release is too early.
8. Cracks may be caused by: the gel coat is too thick, the release is too strong, the structure of the reinforcement layer is too weak; the adhesion between the gel coat layer and the strength layer is poor; the formula is not correct.
9. Poor adhesion to the reinforcement layer may be caused by: the upper reinforcement layer is too late; dust, moisture pollution; release agent pollution; the upper reinforcement layer is inappropriate.
10. Foaming may be caused by: dripping catalyst in the gel coat; water, solvent pollution; poor wetting of the glass fiber; air cells between the gel coat layer and the reinforcement layer; the gel coat and resin are contaminated .
11. Low gloss, the reasons may be: high humidity and low room temperature; low gel coat temperature; poor mold quality or low mold temperature; unqualified mold pretreatment; mold surface is dusty and dirty; gel coat layer is not fully cured When peeled off from the mold; the gel coat has not yet cured completely.
12. The localized yellowing may be caused by: the gel coat is too thick; the gel coat is not cured completely; the gel coat is peeled off from the mold when it is not fully cured; the resin exotherm is too high; the mold cleaning or polishing is not enough.