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Thread: Oratex Fabric Covering Revisited

  1. #61
    Senior Member jtpitkin06's Avatar
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    Default Re: Oratex Fabric Covering Revisited

    I’m pleased that John Evens is sharing his experience. We need first hand input.


    I suppose everyone has an opinion on this product, as do I. What follows is my personal observation and it does not reflect the professional position of any manufacturer, mechanic or distributor of Oratex products. My personal experience with Oratex is a close inspection of an aircraft covered with the product. and spending a week at Oshkosh manning the booth with the factory workers that actually installed Oratex fabric on one of the display aircraft..I do not use their name here because I do not speak for the factory.


    First the appearance. The display aircraft is covered with Oratex white. The finish is flat, not glossy or semi-gloss. It also has a bit of reflective sheen with certain sun angles. This is not a product that gives a model airplane Topflite Monocote type finish. The material is a bit translucent and resembles a nylon petticoat with a primer coat. The fabric weave is very visible… not partially visible as you might see in more traditional fabric coverings. If this is the type of finish you are looking for, then you will probably love it. I am concerned how the airplane might look after exposure to some Georgia red clay dust. I noticed after a week parked at Oshkosh that it was looking pretty dirty compared to conventional covered aircraft parked next to it. We found it very hard to wipe the morning dew off without smearing the dust and dirt into the weave. We had to use a water bucket brigade to clean it where the other aircraft we simply squeegee and wipe them down.


    Next is the weight savings. I had extensive conversations with the factory workers that installed the covering.. This company builds lots of LSA’s so they know what the empty weight should be when the aircraft is covered. They stated the weight saving was between 4 and 6 pounds on a Cub size aircraft. If you are a weight fanatic then this product can save a few pounds over the usual fabric and finish with Polytone or Ranthane. A few pounds, yes. Thirty pounds? No way!


    Application. Here is where you get different stories. Oratex says you can do it yourself. The LSA factory people said it took three workers… two stretching clamping and holding while the third was tacking and ironing. The product is not nearly as forgiving when doing compound curves and corners. Because the product is more expensive and the labor is higher, this LSA factory will install Oratext for you; but, it will cost you twice as much. The Oratex cost is compared to conventional covering doing all the steps of Polybrush, Polyspray and Polytone. (It’s just not that difficult to spray an airplane at a factory with a paint booth)



    Fumes. No, it doesn’t smell. You can do it in an apartment and the neighbors will never complain.


    Longevity. This is one area where I don’t have reliable data. Yes I heard they have been using it in Europe for years. That’s nice. They say the UV protection is in the treated fabric. That’s nice, too. Let’s see how it holds up after a few years of Phoenix sun.


    If you are considering this product, I recommend you see an entire aircraft covered in the product prior to making a purchase of materials.. Also attend a session where an aircraft is actually being covered to see any installation problems you might encounter.


    I tried to be fair in my evaluation of the product but my bias clearly shows. It is not my choice primarily because of the appearance. The cost for weight savings is not worth it for 4 to 6 pounds. No paint booth or spraying outside is a plus.


    What I find is the opinion of the product varies widely. After a week on display I heard lots of comments. Some people love it, and others hate it.
    I guess that’s why the make Fords and Chevys. Everyone likes something different.

    John P

  2. #62
    Senior Member HighWing's Avatar
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    Default Re: Oratex Fabric Covering Revisited

    Quote Originally Posted by jrevens View Post
    They say that just about any type paint works well & adheres well to Oratex fabric. Water-based, MEK-based, urethane, epoxy, regular enamel, etc.
    Be real careful with this. Several years ago, I attended a fly-in in Utah hosted by a Rans Build Center. They routinely finished with auto urethanes. I noticed cracks in the paint of some of the airplanes and a couple of the airplanes had spots where patches of the paint had lifted off and these were not old airplanes. Airplane fabrics require a paint that will flex a significant amount. I suspect the build center knew this and the airplane's paint had a flex additive but these additives are typically designed in auto paints to withstand the flex of the plastic bumpers - a little bit different than what you might find with a fabric covered airplane in the prop wash area for example.
    Lowell Fitt
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  3. #63
    Senior Member jrevens's Avatar
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    Default Re: Oratex Fabric Covering Revisited

    Quote Originally Posted by HighWing View Post
    Be real careful with this. Several years ago, I attended a fly-in in Utah hosted by a Rans Build Center. They routinely finished with auto urethanes...
    Absolutely right... good point, Lowell. Oratex actually sells 2 different basic paints - one that is flexible for fabric, & another for fiberglass, metal, etc. I was just trying to respond to a question & make the point that no special prep, other than making sure the surface is clean & oil free, is necessary for paint adhesion regardless of the type of paint.
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  4. #64
    Senior Member jrevens's Avatar
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    Default Re: Oratex Fabric Covering Revisited

    John Pitkin wrote:
    "...I do not use their name here because I do not speak for the factory."

    I wish you would share the name of the company, John... why not? As you said, you're not speaking for them. I talked to a worker at RANS who said he didn't like it, but this was when they were doing their very first Oratex job, and for whatever it's worth, they also do it quite differently in that they sew envelopes. This guy told me they didn't even use finish tapes, but I have no idea if he really knew what he was talking about or not.

    ..."I noticed after a week parked at Oshkosh that it was looking pretty dirty compared to conventional covered aircraft parked next to it. We found it very hard to wipe the morning dew off without smearing the dust and dirt into the weave. We had to use a water bucket brigade to clean it where the other aircraft we simply squeegee and wipe them down."

    Yes, it has a "texture". As I said before, I'm pleased with the look of what I've done so far, but I've seen several Oratex cover jobs that were poorly done, in my opinion. The finished covering can be waxed. Oratex sells a wax also, but any good automotive wax or polish can be used as far as I know. That might minimize the issue you noted, I don't know. I'm planning to wax mine.

    ..."Next is the weight savings. I had extensive conversations with the factory workers that installed the covering.. This company builds lots of LSA’s so they know what the empty weight should be when the aircraft is covered. They stated the weight saving was between 4 and 6 pounds on a Cub size aircraft. If you are a weight fanatic then this product can save a few pounds over the usual fabric and finish with Polytone or Ranthane. A few pounds, yes. Thirty pounds? No way!"

    Maybe we'll really get to the truth of this someday, but I believe that 20 to 25 lbs. is not beyond the realm of possibility. I think the fabric is similar in weight to the bare Polyfiber fabric (I'm going to try to weigh samples of each tomorrow, & I'll report back). If that is the case, then 30 lbs. can easily be added to an airplane of that size with paint. I measured a weight gain of approximately 30 lbs. when I painted my T-18, and it is a smaller airframe with a wingspan of 21 ft. That was 1 coat of primer & 2 relatively light coats of PPG Durathane (no clearcoat).

    ..."Application. Here is where you get different stories. Oratex says you can do it yourself. The LSA factory people said it took three workers… two stretching clamping and holding while the third was tacking and ironing. The product is not nearly as forgiving when doing compound curves and corners."

    I've done it all myself so far... when I get to the fuselage it may be a different story - we'll see. Like many things, it is sometimes helpful to have a few extra hands. It is more difficult for me to do curves, than if I was using bias tape for example. It has gotten easier with experience.

    ..."Fumes. No, it doesn’t smell. You can do it in an apartment and the neighbors will never complain."

    You also won't hurt yourself. One of the biggest reasons for some people to use it... it is completely non-toxic & environmentally safe.


    ..."Longevity. This is one area where I don’t have reliable data. Yes I heard they have been using it in Europe for years. That’s nice. They say the UV protection is in the treated fabric. That’s nice, too. Let’s see how it holds up after a few years of Phoenix sun."

    True. 10 years in Europe. Any non-hangared fabric airplane is going to take a beating in Phoenix, or anywhere else for that matter. It's a question mark in my mind.


    ..."If you are considering this product, I recommend you see an entire aircraft covered in the product prior to making a purchase of materials.. Also attend a session where an aircraft is actually being covered to see any installation problems you might encounter."

    Good advice. I agree 100%.

    ..."What I find is the opinion of the product varies widely. After a week on display I heard lots of comments. Some people love it, and others hate it."

    Same thing, for instance, with the Stewart System.
    John Evens
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  5. #65
    Senior Member jrevens's Avatar
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    Default Re: Oratex Fabric Covering Revisited

    OK, I cut 2 one square foot (1'x1') samples of medium weight Polyfiber fabric & Oratex 6000. The results:

    Polyfiber - 0.35 oz./sq.ft.

    Oratex 6000 - 0.50 oz./sq.ft.

    I have calculated that it takes approximately 45 sq. yards of material to cover a Series 7 SS Kitfox (I have cut all of the pieces - oversize - to do that, out of 50 sq. yds., with some left over). That gives us a projected fabric weight of approximately:

    8.86 lbs. for Polyfiber &

    12.66 lbs. for Oratex

    So the finished difference is going to be close to whatever the Polyfiber paint job weighs minus a little under 4 lbs.

    I think that 20 to 25# is a perfectly reasonable estimate... it could be more, it could be less.

    A couple of other thoughts - the "textured" surface has been discussed as possibly being an aerodynamic plus (think golf balls, turbulator tape, etc.). That's probably a stretch, but who knows. Something else not mentioned by John P. is that the Oratex is considerably stronger. Other than the "classic look", it's got a few real pluses going for it.

    Finally, I sure don't want to be responsible for anyone else using Oratex based on my experiences & reports alone. I do like it so far, but there are some question marks, and I realize that I'm being a little bit of a Guinea pig. You probably know how that feels with your choice of engines for your 'fox, John P.
    Last edited by jrevens; 08-26-2014 at 01:48 PM. Reason: Added a thought
    John Evens
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  6. #66
    Senior Member HighWing's Avatar
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    Default Re: Oratex Fabric Covering Revisited

    Quote Originally Posted by jrevens View Post
    OK, I cut 2 one square foot (1'x1') samples of medium weight Polyfiber fabric & Oratex 6000. The results:

    Polyfiber - 0.35 oz./sq.ft.

    Oratex 6000 - 0.50 oz./sq.ft.
    I'm going to chime in here largely because the covering weight issue has been going on for forever. In fact, I have been a skeptic forever.

    First, the Polyfiber medium weight fabric is listed at 2.79 Oz. per Square Yard. The .35 oz. per sq. ft. would give a square yard figure of 3.15 oz per sq. yd. I can't explain the discrepancy. If it is scale error it would also affect the Oratex weight mentioned above. I weighed a sample of my own cut to exactly 1 sq. ft. and it weighed 2.70 oz. Be that as it may, I have always been a skeptic on the actual weights claimed for covering and painting. For some reason, I don't think that people who claim high covering weights using 50 lbs. of covering chemicals consider that the vast majority of that evaporates leaving a fraction of what is actually applied adding to the empty weight.

    By coincidence, I am covering an elevator for an Avid. We redid the trailing edge to give more cord and added a trim tab modification. I am using Polyfiber. Using John's example, I have cut a very precisely measured one foot square piece of medium weight Polyfiber cloth. What I will be particularly interested in is the actual weight of the residual chemicals as I take it through the finish process with all the coatings up to final coats. I may even go there if time permits. I have finished the elevator to the first spray coat of Polyspray. I have done the same to my square foot sample.

    I have attached a PDF of the spreadsheet I am using to save the numbers. As mentioned, I have a column that reflects the net addition of the chemicals to the basic cloth. I don't know if it is valid, but I presumed the fabric adhesives would be pretty much a wash on each technique. Another thing I did for completeness is add an estimated amount of 2" finish tape. I did this because the finish tape will absorb a certain amount of the Polybrush and will add its weight to the total as well - along with the weight of the tape. My estimate was one foot of 2" finish tape per square foot. I also used the .300 oz. per sq. ft. of my sample which reflects more accurately the fluid totals per square foot.

    The finish coats supplied by Polyfiber are much thinner than the typical automotive urethane coatings so my estimate is that they will be quite close to the weight of the spray coat already applied. If the aluminum coating is twice the weight of the spray coat and the final finishes are three times the spray coat, it would only add 8.7 lbs to the total covering weight and this includes finish tapes. - time will tell.
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    Last edited by HighWing; 08-27-2014 at 07:32 PM.
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  7. #67
    Senior Member jrevens's Avatar
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    Default Re: Oratex Fabric Covering Revisited

    I'm really glad we're having this discussion also. It's good to get some "real world" experience and data.
    If you meant 0.27 oz. for the sq. foot of fabric, Lowell, that would give you 2.43 oz./sq. yd. - considerably less than the published Polyfiber data. I used a calibrated electronic scale, but I can't personally verify it's accuracy without test weights. I wonder about the accuracy of your scale too. However, like you said, any inaccuracy would probably occur with both samples. I look forward to your experiment with finishing the sample, as I would like to know the true weight of the paint also. That's the most important piece of data.

    Of course I have thought of the fact that the volatile components of paint evaporate, and also that there is a lot of difference in "cured" vs "wet" paint weight depending on the amount & type of "solids", the curing method, etc. The wet vs dry weight difference is going to be greater with Poly-Tone than with a urethane or epoxy finish. This makes the difference between the weight of a gallon of liquid paint versus the cured or dried result of that gallon much greater with the Poly-Tone for instance. There will be more evaporation of components

    On my T-18, I weighed everything I could, before & after painting, to come up with the 30# figure. I weighed & painted the rudder, vertical fin. stabilator, ailerons, flaps, wing panels, wing tips, wheel pants, gear leg fairings, etc., etc. all separately. I then estimated the fuselage based on that experience. Believe me, it was very accurate.

    Finally, if you are painting your sample with Poly-Tone, I believe that the finished weight might be considerably heavier with Aero-Thane... just a guess.
    John Evens
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  8. #68
    Senior Member HighWing's Avatar
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    Default Re: Oratex Fabric Covering Revisited

    Thanks John for calling attention to the typo. It should have read sq. yard as the sq. ft. weight was .300 oz. Just too many numbers for this old guy.

    (Edit) I do have some calibrated weights and find that my scale weighs 1% high. Multiplying all weights by .99 gives a corrected weight - not enough to worry about so I am going to continue to use scale weights.

    I would also welcome hearing abouit any errors anyone might find on the spreadsheet.

    I plan on painting with aerothane. I'll have to think about the possible differences between the weights of cured and evaporative drying. It takes about a week before you can wipe the aerothane with solvents before it is fully cured, so it would be lightened considerably with evaporation before final cure. Aerothane is thinned 3:1
    Last edited by HighWing; 08-27-2014 at 08:34 PM.
    Lowell Fitt
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    Senior Member jrevens's Avatar
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    Lightbulb Re: Oratex Fabric Covering Revisited

    Another bit of interesting info from Poly-Fiber's website, "Frequently asked questions" -

    "When Cubs rolled off the line, they had 75 pounds of Grade A cotton and dope on them.

    A Ceconite and dope finish on that same Cub will probably weigh about 50 to 60 pounds.

    A Cub done in Poly-Fiber has 40 to 45 pounds of finish weight.

    A Cub done in urethane can get pretty heavy if you lay on the thick coats. Urethane is not known for its light weight.

    Ultralights can be done in as little as 12 to 15 pounds."


    I'm believe that there must be a LOT of possible variance in weight of paint jobs due to application techniques & "desired look", not to mention type of paint. Those things are taken out of the equation with Oratex. I also wonder if there is some possibility that the weight of Polyfiber fabric varies from batch to batch. It seems unlikely, but that might explain the difference between Lowell's & my 1 sq. ft. samples. I did obtain some test weights last night & verified the accuracy of my scale.
    Last edited by jrevens; 08-28-2014 at 09:16 AM. Reason: Added thought
    John Evens
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  10. #70
    Senior Member HighWing's Avatar
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    Default Re: Oratex Fabric Covering Revisited

    Regarding weight comparisons, the elevator I have been working on, is finished to the two cross coats of white. I added these weights to the spreadsheet to give final results of the chemical weights up to the white Aerorothane only.

    I would like to make several comments as to methodology.

    I added a two inch strip of pinked medium weight finish tape to the square foot of fabric. An eyeball inspection of my model IV suggested about that much tape per square foot was on the finished airplane. Many of the tapes I used were one inch wide - false ribs and empennage ribs. The weight of the finish tape includes the weight of the Poly brush required for attachment. I took the liberty to add the same to the Oratex weight per square foot as that covering process also uses finish tapes. The weight was determined by calculating the weight of a 2" wide strip of the fabric based on John's measured weight.

    My current Model IV has two colors. 100% of the surface is covered in Insignia White - as in the measured sample - as a base coat and an estimated 50% is painted in Lemon Yellow for the overall scheme. The numbers for the white is measured from the sample and the yellow is calculated as an estimated percentage of the white. This was to give me an estimate on the fabric weight for my personal airplane. If an Oratex covered airplane had a decorative design added either by painting or gluing on different fabric colors, it would add to the overall weight, but how much was impossible to estimate.

    An explanation of the results: The fabric combined weight refers to the sq. ft. of fabric plus an estimated 1 foot of 2" finish tape per sq.ft. The chemicals combined refers to the net weight of each additional layer of chemical - Polybrush, Polyspray and Aerothane - Not including the yellow. This was to compare equally finished airplanes. However the net increase of the yellow is indicated.

    The final weight comparison between the Polyfiber process and the Oratex process is given at the bottom in both white and with the estimated yellow weight. The combined Oratex weight includes the estimated finish tape weight.

    Finally, I can think of at least one variable that would influence the final weight vs. my measured square foot extrapolation. Possibly reducing total chemical weight by approximately two pounds. It is that not all of the fabric actually applied in the Polyfiber pricess has the finish chemicals applied to the surface because all fabric underlying seams would have none of the brush or sprayed coats of chemical. For example the 3 inch (or more) overlap on the leading edge of the wing would reduce the overall fabric surface by about 3.5 sq. ft. That would reduce the total applied chemical weights by a small fraction over one pound. To a lesser extent there is a half inch to one inch overlap on every foot of seam - leading edge, trailing edge and longeron length. The best way to get close total weight differences is by, as John Pitkin suggests, a manufacturer that uses the two systems in airplanes built to an exacting design and graphing the weights over time - SLSA.

    Finally, I was surprised that the weight of the white Aerothane was as high is it was given that the pigment is titanium dioxide.
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    Last edited by HighWing; 09-10-2014 at 10:04 PM.
    Lowell Fitt
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