1. Product Mixing Ratios
U500 For attaching fabric to the frame: 2 parts U500 : 1 part Acetone or MEK For attaching surface tapes: 1 part U500 : 2 or 3 parts Acetone or MEK
Epoxy Primer 1 part SF80 Epoxy Primer : 1 part SF820 Epoxy Primer Catalyst Use any of the SF7800-series reducers to thin to a sprayable viscosity.
Epoxy Varnish 1 part SF90 Epoxy Varnish : 1 part SF920 Epoxy Varnish Catalyst Use any of the SF7800-series reducers to thin to a sprayable viscosity.
System 7 Fabric Primer 4 parts SF7500 Fabric Primer : 1 part SF7600 Fabric Primer Catalyst Reducer: Use anything in the 7800-series to thin to a sprayable viscosity. First coat of primer needs to be thinner than the second coat of primer. The first coat fills, and the second coat builds.
System 7 Superflex Topcoat 2 parts System 7 Superflex Topcoat to 1 part SF8950 topcoat catalyst. Thin with a 1/2 part of any of the 7800-series reducers.
2. Fabric Shrinkage
All of Superflite’s fabrics need to be shrunk at three different temperatures: 250º, 300º, and 350º.
3. How to use the U500 fabric adhesive
The U500 glue is used for attaching both the fabric to the airframe and the surface tapes to the fabric. Acetone or MEK can be used to thin the U500 to the proper viscosity. Do NOT use butyrate thinner, urethane reducer, or lacquer or enamel thinner. Only acetone or MEK. The U500 is NOT meant to be used as a fabric filler. It is only to be used to attach the fabric to the frame and the surface tapes to the fabric. When applying the U500 to the airframe, it needs to be applied anywhere fabric will be touching structure. Some of that glue may not necessarily be activated, but it needs to be applied everywhere. This adhesive acts as a barrier in those areas and prevents the primer from “wicking” underneath the fabric. Wicking occurs when the primer “slips” under the fabric instead of soaking into the weave as it’s intended. When attaching the surface tapes to the fabric, be sure not to apply to much glue. A visible glue line along the tapes will show through to your finish. If you find that you’ve used too much glue, just soak a clean rag in acetone or MEK and clean up the edges.
4. Recommended tools for fabric covering
- Clean and empty cans for thinned U500
- Natural bristle brushes for applying U500
- Superflite Gluemaster glue gun
- Iron – at least 1100 watts – for shrinking the fabric
- Thermometer for calibrating the iron
- Safety goggles
- Shop towels or paper towels for clean up
- Saw horses
5. Recommended spraying equipment for using Superflite
To get the best finish possible, the Superflite technical department recommends the following:
- Use a gravity feed gun for spraying both the primer and the paint.
- Because it’s a thicker product, the Superflite fabric primer requires a large nozzle – 1.8-2.0 mm.
- The paint needs a smaller nozzle – for the overall color, 1.5 mm works well. For any trim color, use a 1.3 mm nozzle.
- A good primer finish can be achieved by using an HVLP turbine unit, like the Axis Citation unit that Superflite carries.
- For a good quality show finish with the topcoat, we recommend using the DeVILBISS FinishLine brand of products – their air control unit and gravity feed gun.
Problem: Fish Eye - Fish eye is pretty recognizable – they’re small crater-like holes in the paint surface, typically larger than pinholes – and they look like a fish eye. The most common cause of fish eye is contamination – on the substrate, in the gun, in the air. The only way to fix it is to sand below the actual fish eye, thoroughly clean the surface and all of your equipment, and then shoot again.
Problem: Orange Peel - Orange peel is a pebbled and uneven surface in the paint coat, similar in appearance to the peel of an orange. The most common causes of orange peel are poor spraying technique and not using enough reducer. If you’re experiencing orange peel, sand the surface and spray again. Before spraying again, be sure you’re using a proper spraying technique (you’re far enough, but not too far from the surface. 10-12 inches in a good distance), and be sure to use enough reducer. On the topcoats, we recommend starting at around 20-30% on the reducer.
Problem: Pinholing - Pinholes are small cavities, less than 1 mm in diameter, and generally occur in the primer coats. Typically pinholing occurs when too much product is piled on too quickly. To correct this, you’ll need to sand down the pinholed areas and reshoot. Before reshooting the product, be sure the area you’re respraying is smooth. Make sure the primer is mixed correctly and allow plenty of dry time between coats.
Problem: Product is slow drying - The primer and paint coats are taking an inordinant amount of time to dry or they’re failing to harden completely. If the product is slow to dry, generally there’s been insufficient drying time between coats, the ambient temperature is too low, incorrect mixing ratios have been used, or the incorrect catalyst has been used. To correct a drying problem, try moving the plane to a warmer and well-ventilated area. Turning on a space heater might help, but exercise caution. Don’t leave the space heater unattended, and don’t get it too close to the airplane.
7. Making a repair with Superflite
The inability to make repairs is a common myth with urethanes, particularly Superflite. However, Superflite is very easy to repair. If you’re making a small patch repair, scuff the area just two inches beyond your tear. Apply a thinned coat of U500 to the sanded area. Cut a patch and place it over the sanded and glued area. Use another thinned coat of glue to get the patch to stick. Once dry, shrink the patch at 275º and again at 350º. Apply the fabric primer, and sand smooth. Then apply the topcoat. A blending agent can be used to feather out and blend the edges of the repair.