Guide to surface finishing with
Epoxy Resin & Woven Glass Fibre Cloth.
A METHOD FOR WING FINISHING USING A ROLLER.
This guide outlines a alternative method for covering surfaces which require a hard, lightweight durable finish and uses the specially formulated epoxy resin which is applied using a roller applicator and a resin spreader card. Other methods for application are possible using vacuum bagging techniques methods but the following this method yields excellent results. The roller method can be more acceptable than using the credit card technique, for example it can be cleaner and quicker and a uniform coating can be easily achieved without dragging the glass fibre cloth.
Component to be covered e.g. a wing
- Super lightweight fairing compound
- Absorbent paper (Loo roll)
- 220 & 400 grit wet & dry sanding paper
- Bucks sanding pad
- Dust mask & surgical gloves
- Bucks epoxy resin Surface Finishing Kit 2 or 4 metre
- Bucks 2” Foam Roller Kit
Operate in well ventilated flame free area and use protective gloves whilst handling epoxy resins. Also operate in a dust free environment to ensure a quality finish. When sanding wood or cured resin then always wear a mask as the particles are not friendly.
Take into consideration heat generation when mixing resin and hardener, once mixed put into a larger area this will prevent higher temperature build up and this will give you a longer pot life (working time). Never mix large quantity of resin and hardener.
- Sand the entire surfaces smooth with the Bucks 400 grit sanding pad dry.
- Working on one side, fill any imperfections in the wing with fairing compound mixed with activated epoxy resin following the instructions on the containers. Smooth over and allow to dry for 24 hours before with 220 grit sanding paper. Now repeat the process on the other side.
- Ensure that after smoothing, all traces of wood dust are removed.
- Assemble the foam roller onto the roller handle.
The two weights of glass cloth I recommend are 25g & 49g per square metre.
- 25g Glass Fibre Woven Cloth, Ideal for models up to 70" wingspan or up to 10lbs all up weight.
- 49g Glass Fibre Woven Cloth, Ideal for models over 70" wingspan or over 10lbs all up weight.
THE WING IS NOW READY FOR GLASS CLOTH TO BE APPLIED.
- Support the wing with underside uppermost such that the edges of the wing are unobstructed. (The wing could be supported on old margarine containers or similar). Turn the wing over so the underside is on top. Work on the underside first.
- Cut the woven glass fibre cloth with sufficient to allow an overhang of about 25mm (1”) all round. If the wingspan 2 metres or less then the entire underside could be covered in one piece of cloth. Otherwise cut individual wing panels.
- Lay the selected woven glass fibre cloth onto the wing and smooth out any wrinkles with hand. A tip here is to clip clothes pegs about 75mm (3”) apart onto the edge of the glass cloth and the weight of the pegs drape the glass cloth halfway around the leading and trailing edge of the wing.
- Best results are achieved by mixing small batches of activated epoxy resin between 60ml to 150ml and make sure the activated epoxy resin is well mixed and pour this into a roller tray. Soak up this activated epoxy resin into the roller and roll it onto the glass fibre cloth working from one end of the wing to the other end.
- Working your way down the wing until the entire batch of activated epoxy resin is used up. Keep rolling the resin until full saturation of the surface has been achieved on one side of the wing. Mix up small batches of resin and hardener as you use it. Notice the colour change from white to clear as you saturate the glass cloth.
10. Check to see if there are any surplus glossy areas of resin on the wing and if there are then these need to be soaked up using a loo roll rolled down the entire length of the wing discarding the wet paper as you go. Surplus resin will only add weight to the model.
11. Remember only leave enough activated resin to stick the cloth to the wing to keep weight down to a minimum. The tray can be washed out with epoxy thinners and the foam roller cannot be cleaned. Leave to cure in a warm dust free area for 24 hours.
12. Ensure that the activated epoxy resin on the surface has completely cured before you remove the clothes pegs and sand back the edges of the overhanging cloth halfway round.
13. Turn the wing over and repeat the entire process on the other side leaving to fully cure.
14. When sanding off the glass cloth overhang usually the edges have 2 layers of cloth on the edge.
15. If a gap should appear between the two edges of the glass fibre cloth, then fill with a small quantity of activated epoxy resin using a brush.
16. Gently rub down the top and bottom surfaces, with 400 grade wet/dry paper used wet. Add a few drops of washing up liquid to the water and rinse the paper frequently.
17. Dry the wing with absorbent paper.
18. The wing is ready for painting with a high build filler primer from Halfords.
Superior results will be achieved if the work area is heated (winter time) and a warm temperature maintained. Failure to do this will prevent the resin from curing properly. Work area should be free from dust and have low humidity for best results.
Winter time: The resin in the container can form crystals. With a hair dryer warm the resin in the container until all the crystals have all gone. Now the resin is safe to use.
Summer time: The activated epoxy resin can be dispersed into a roller tray to prevent heat build up and this will also give you a longer working time.
Storage: The epoxy resin and hardener will last more than 12 months if stored in the dark at room temperature.