Painting a patch on Ranthane

[arborite]

I just got a nasty hangar rash on my J5. Leading edge of wing was scuffed by a hangar door and made a small tear in the fabric. my plan is to repair it with a patch using the Stewart’s system products due to ease of handling it and my neighbor has everything i need except paint. The fabric and finish of the plane is otherwise in excellent shape. It was recovered with Polyfiber and painted with Ranthane a few years ago and looks nearly new. Stewart’s products are compatible with this combination according to them.

Question for the painters out there - do I have to use Ranthane as the topcoat or can I use the Stewart’s polyurethane? Obviously I need to paint the small (4” x 5”) patch but also have to blend it in to the adjacent areas that are the original Ranthane. Aside from the color match issue, is there any problem painting the water based Stewart’s Ekopoly over the Ranthane?

 

[Bearhawk Builder]

From the Stewarts Manual -
NOTE: STEWART SYSTEMS is certified to repair any other certified covering system using the following procedure. Repairing fabric damage with STEWART SYSTEMS method is a relatively simple and easy process. In the case of a fabric puncture, the area must be thoroughly cleaned with STEWART SYSTEMS EkoClean Heavy Duty Cleaner (E670) to remove any waxes, silicones, or contaminates which might be present. If the topcoat is STEWARTSYSTEMS Waterborne Catalyzed Polyurethane, just scuff sand an area 2” around the damaged area before patching. If you are unsure of the topcoat or you know it is something other than STEWART SYSTEMS Waterborne Catalyzed Polyurethane TopCoat, you must sand through the topcoat to the primer or UV coat 2” around the damaged area. Next glue your patch on the sanded area using EkoBond glue and allow to dry completely. The glue joint must be a minimum of 1” around the perimeter .Heat shrink the fabric ONLY over the open hole under the patch. Finish Iron the patch edges at 250°F. Apply EkoFill to desired thickness, sand and spray or otherwise apply matching topcoat. For more information, refer to previous sections of this manual.

 

[skywagon8a]

I've used Valspar over Stewarts with success. Color matching can be perfect. Cost is a lot less.

 

[arborite]

From the Stewarts Manual -
NOTE: STEWART SYSTEMS is certified to repair any other certified covering system using the following procedure. Repairing fabric damage with STEWART SYSTEMS method is a relatively simple and easy process. In the case of a fabric puncture, the area must be thoroughly cleaned with STEWART SYSTEMS EkoClean Heavy Duty Cleaner (E670) to remove any waxes, silicones, or contaminates which might be present. If the topcoat is STEWARTSYSTEMS Waterborne Catalyzed Polyurethane, just scuff sand an area 2” around the damaged area before patching. If you are unsure of the topcoat or you know it is something other than STEWART SYSTEMS Waterborne Catalyzed Polyurethane TopCoat, you must sand through the topcoat to the primer or UV coat 2” around the damaged area. Next glue your patch on the sanded area using EkoBond glue and allow to dry completely. The glue joint must be a minimum of 1” around the perimeter .Heat shrink the fabric ONLY over the open hole under the patch. Finish Iron the patch edges at 250°F. Apply EkoFill to desired thickness, sand and spray or otherwise apply matching topcoat. For more information, refer to previous sections of this manual.

Yes, I’ve read that, but it doesn’t say anything about the Stewart’s topcoat being compatible with a Ranthane adjacent paint. Assuming I can use the Stewart’s paint for top coat, what is the prep for the surrounding area? I think I’ll try scuffing it with 220 grit and giving it a try. Applying Ranthane will work fine, but I’d like to avoid the cost and equipment needs of that solution for just one patch.

 

[Steve Pierce]

Getting the Stewart paint to match the Ranthane color would discourage me. Poly-Fiber is easy to patch. I have never had luck blending catalyzed polyurethane. I find a tape line and pink my masking tape. When the final coat is still tacky I pull the adjacent tapes to allow the paint to flow and reduce the hard edge.

I use Stewart glue a lot to glue a painted surface patch right over any covering system without having to sand or anything. We have an endless supply of patches we have saved from the wrecked Carbon Cubs we have repaired.

 

[stewartb]

Steve Pierce has the right answer. Stay with the Ranthane. Mask carefully because any seam at the new paint will show. Get some super thin detail tape to minimize the paint line. It may be easiest to mask a section larger than the patch, like a section of the leading edge. If you paint over existing paint, you’ll need to sand the surface so the new paint sticks.

 

[bob turner]

I don't spray stuff with cyano- chemicals, but like Steve and Stewart, I pink the masking tape for repairs, then try to line up edges as if it were where a surface tape would have been. With Butyrate, I can compound the edges so they barely show. I have a couple Bahama Blue patches on the Decathlon where you cannot tell there was ever a patch.

Like Steve, I have had no problems at all with Stewarts glue, and I like the way the Eko-fill wet-sands (Stewarts says dry sand).

Color matching is no longer easy - especially yellow. Back in the olden days you just ordered the color you want and it was a perfect match. Cub Yellow, Juneau White, and Colorado Red are now different - sometimes dramatically.

 

[Bearhawk Builder]

Yes, I’ve read that, but it doesn’t say anything about the Stewart’s topcoat being compatible with a Ranthane adjacent paint. Assuming I can use the Stewart’s paint for top coat, what is the prep for the surrounding area? I think I’ll try scuffing it with 220 grit and giving it a try. Applying Ranthane will work fine, but I’d like to avoid the cost and equipment needs of that solution for just one patch.

First line covers it.

 

[bob turner]

I think the Stewarts topcoat is in the neighborhood of urethane, both for cost and precautions. I might be wrong on that- I have priced neither lately. I think Stewarts recommends full body covering, but not sure on the external air.

For very small repairs we have an outfit that makes exact match paint in rattle cans. Really expensive - $125 for three cans - and no plasticizer. But we are using it successfully on patches on top of urethane.

 

[stewartb]

Ecopoly is urethane. Coating over cured urethane will require abrading for tooth adhesion since chemical bonding won’t work. Regardless of the paint chosen, color match will be the most important thing and any of the paints is going to leave a raised edge at the mask. You can try polishing to diminish the edge but you’ll probably do more harm than good.