FAQ about FRP Laminates

This section is dedicated to the most common questions we receive from our customers about FRP panels, the materials used, fibreglass, the gelcoat, the finishes available and the maintenance and repair of panels, etc. Please do not hesitate to contact us for further information.

01. What is fibreglass?

Fibreglass is a composite material composed of a polyester resin matrix reinforced with glass fibre. The combination of these two materials creates a material with good mechanical properties and high chemical resistance.

02. What is gelcoat?

Gelcoat is an external finish applied to the laminate; it consists of a strongly coloured polyester resin, with a thickness of about 300 microns. It gives the laminate a pleasant appearance and good chemical resistance, making it easy to clean and suitable for use with food.
The gelcoat is applied using hoppers, with a thickness varying from 300 to 350 microns. The thickness and manual nature of the process mean it is not possible to guarantee a tolerance for the thickness of the gelcoat. However, we can guarantee that on average 450 g/m² of gelcoat is distributed in the roll.

03. What colour are the laminates?

The standard colour of our laminates is pure white (obtained using titanium dioxide as the sole pigment), which is similar to the RAL 9010 colour; however, laminates produced by Vetroresina can be produced in various RAL colours or even in customised colours.

04. Can the laminates be painted?

Yes, laminates with a gelcoat finish can be painted using standard bodywork paints. Before the material can be painted, the surface must be prepared by sanding it down using sandpaper of various grades followed by the application of a base coat.

05. Can fibreglass be repaired?

Yes, laminates with a gelcoat finish produced by Vetroresina can be repaired by painting the material with traditional paint (polyurethane, acrylic, etc), applying a layer of gelcoat for repairs or applying a polishable polyester resin sealant.

For more informations please download the pdf INSTRUCTIONS FOR GELCOAT REPAIR.

06. What is GLOSS?

Gloss is a parameter used to indicate the degree of shine of the laminates and is measured using specifically designed instruments called glossmeters.

07. What is the GLOSS value of the laminates?

The gloss of the laminates depends on the mould used. Vetroresina can supply glossy products (with a gloss value of between 85 and 95) or matt products (with a gloss value of between 15 and 20).

08. How do you clean fibreglass laminates?

They can usually be washed with soap and water. Thanks to the resistance of the gelcoat finish, various solvents can be used (acetone for example) to eliminate stubborn stains (grease, glue, etc).

09. What is the specific weight of fibreglass?

The specific weight depends on the glass content, which is very high in products produced by Vetroresina. It can vary from 1.3 g/cm³ (thin products with a low glass content) up to 1.6 g/cm³ (thick products with a high glass content). VETROLITE has a very low specific weight, equal to about 1.1 g/cm³.

10. Is fibreglass fire resistant?

The standard laminates produced by VETRORESINA are composed of glass fibre and resin that is not self-extinguishing and may be classed as a Class C flammable material, with fire behaviour similar to materials such as wood, paper, etc. The average calorific strength of polyester resin is around 18.8 – 30.1 MJ/Kg. Glass fibre is not a flammable material.
Vetroresina also produces a special range of Fire Resistant (FR) Laminates certified in accordance with the main European regulations with various degrees of fire resistance.

11. At what temperature range can laminates be used?

Fibreglass laminates can be used at temperatures of between –30°C and +70°C, although it is recommended that they be conditioned at room temperature (20-30°C) before being handled and used.

12. What is HDT?

Heat Deflection Temperature (HDT) is the temperature at which a determined amount of deflection is achieved (usually 0.25mm) when a determined load is applied (0.45MPa or 1.8MPa). The test is usually performed by securing the two ends of the test piece, with supports placed 102 mm apart, and placing the weight in the centre.
The measurement is started at a low temperature, which is then increased by 2°C/min. When deflection at the centre of the test piece reaches 0.25 mm, the temperature is recorded.
A number of factors can affect this value, above all: product thickness, the load applied at the different temperatures, the method of construction and the conditions in which the material is applied. This means it is often difficult to use the HDT value to reach any conclusions about the material’s performance during use, indeed if the load is increased deformation occurs at lower temperatures.
The HDT of the resin used to produce our laminates is 80 °C.

13. What are the main defects or faults that may be found on laminates? What are the causes?

Vetroresina has produced a Catalogue of faults to help customers interpret and understand the main faults that may be found. The production method used by Vetroresina (discontinuous process) may result in a small percentage of imperfections.
If faults of a considerable extent are identified, please report them to us using the normal complaints procedure.