The Dope Systems – Ceconite and Superflight System I

 

Things that hold true for both Dope Systems

 

As dope ages, the solvents and plasticizers in the finish evaporates or just migrate out of the finish. When this happens it will get brittle and start to crack or ring worm. To keep this from happening, the finish can be rejuvenated.  This is done by spraying or brushing the “Rejuvenator” on the old finish and as it soaks in it replenishes the solvents and plasticizers to  restore the suppleness.

 When using dope finishes on fabric you will need a different type of paint for the metal and fiberglass.  Dope just does not work well on metal and fiberglass; it does not adhere well and will scratch off very easily.  Each fabric system has its own recommendation for what paint to use on the metal and fiberglass.

 The dope systems use more coats of finish than the other systems, but dope is cheaper per gallon than other paint so the overall cost is about the same. When dope is sprayed on the solvents soak in to the previous coats which meld it all together. Because of this soaking in, it is generally recommended that only 2 cross coats be put on per day.  Put one coat on in the morning and one coat on in the afternoon. This allows for the solvents to stabilize and the finish not to mush up.

One big advantage of the dope systems is that the dope is very easy to spray on. Being mostly solvents, it just flows and smoothes out.  You really have to work at it to get a bad finish when using dope.

 The disadvantages to Dope are that it is extremely flammable and that typically it is heaver than the other Dacron based systems.  That being said, the systems using Dacron and dope are much lighter than the old cotton and dope system.  Weather is also a concern when spraying dope, both temperature and humidity are very important for a nice job.

 

 Ceconite™ System, owned by Consolidated Aircraft Coatings

The Ceconite™ System is a Nitrate–Butyrate dope system and is one of the earliest systems that was developed and approved that uses Dacron fabric.  For the STC to be valid you must use Ceconite™ brand fabric. The fabric is glued down with their Super Seam cement.  The ironing, heating, shrinking is only up to 250 degrees, not 350 like the other systems. To seal the fabric, Ceconite™ uses Rand-O-Proof™, which is tinted green or clear Non-Tautening Nitrate dope.  The finishing tapes are attached with either Rand-O-Proof™ or Non-Tautening Nitrate dope. UV protection is by using G-6303 Rand-O-Fill™, which is their silver.

 For the top coat in the Ceconite™ system you have a choice of either Colored Butyrate Dope or Ranthane™ which is a polyurethane paint.  The dope will give a “traditional” finish and as it ages and starts to get dry you have the option to rejuvenate it.  The Ceconite™ system recommends using Mark II for Metal or Ranthane™ for the metal or fiberglass components. The Ranthane™ polyurethane finish gives a nice glossy wet look finish which is more durable than the dope finish and it can be used on all surfaces of the plane. Ranthane™ is also much less apt to stain than the dope finish.  The disadvantage to Ranthane™ is that when the underlining dope starts to dry out and crack as it ages, it can not be rejuvenated.

 Repairing damaged fabric requires taking the finish off the fabric down to bare cloth, gluing on the patch and then building up the finish again. The amount of overlap on the patch depends on the size of the repair.

  As a safety note, when spraying dope you should wear a respirator at all times.  When spraying Ranthane™ or Mark II for Metal, a fresh air breathing system is required.

 

Superflight System, System I

Superflight System I is the other Dacron and dope system that is available.  They also have their own fabric that must be used for their STC to be valid.    They have their own Urethane adhesive U500-01 that is thinned down using MEK or acetone to attach the fabric. The fabric is heat shrunk to 350 degrees and is attached to the ribs in the normal ways. The finishing tapes can be attached using either thinned U500-01 or clear dope. The fabric is sealed using Dacproofer™. Once the fabric is sealed and encapsulated by Dacproofer™, the UV protection is provided by SpraFil™ which is their silver.  The topcoats and color are tinted Butyrate dope.    Superflight suggests using their Urethane top coat paint for all metal and fiberglass.  Because this is a dope finish it can be rejuvenated, as it ages and starts to dry out, to help keep it supple.

 To repair Superflight System you have to remove all the dope down to the bare fabric.  Once it is all cleaned off, then glue on a patch and build the finish back up again.

 As a safety note, when spraying dope you should wear a respirator at all times.  When spraying the Superflight Urethane topcoat a fresh air breathing system is required.

 

 

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