Nitrate Dope

Discussion in 'Tools of the Trade' started by Gil, Apr 5, 2005.

  1. Gil

    Gil Active Member


    Barry, took me the longest time to figure out what I was looking at..., thats an alligator clip holding the tube, right?

    The images below show small clamps for pushrod clamps on a small diameter needle and two, a gun barrel roll (which doesn't show the taper due to keystoning effects). Rolling small diameter is now actually kind of fun except the really small stuff can get lost easily so make a few more than you actually need.

    Best regards, Gil


  2. gera

    gera Member

    Re: small diameter tubes

    Barry, that's exactly how I make "landing gear struts"...I use a heavy type of tissue paper, the kind they use in stores to wrap up clothes and put them in a box :? ........You can practically get any diameter. I is so manageble you can cut a small square and roll it with the pin. I always roll it and once its like I want it I roll it again with my fingers covered in white glue, once dried I cut them to the length I need. :)
  3. Leif Oh

    Leif Oh Member

    Gil, those small tubes really look terrific. Could you explain, in a few words, what "vellum" paper is? I have a book of thin tracing paper - would that be it? (Seems it would be very good also for making wheel-axes, etc., fit more snugly. - Leif
  4. Gil

    Gil Active Member

    Leif, it's drawing or translucent tracing paper. It has a fine "tooth" texture for absorbing ink. It is hard to find without the blue grid but it can be found (haven't investigated artists tracing paper yet). It is 0.08 mm (0.003 in) in thickness and the source I am using contains 25% rag (cotton linters). It's very tough and stiff and rolls extremely small tubes without disintegrating as does regular bond paper. Applying the instrument lacquer hardens the entire tube into a replacement for styrene products. Funny you should mention wheel axles, that was exactly my thoughts on it too...,
    Gerado, the reason for using the pins in rolling is to insure an inside diameter dimension - important if the result is to fit onto the outside of a shaft and to maintain a semblance of scale proportion. Free rolling is the easiest way to get the tube small and the double vinyl eraser trick takes it one step smaller with ease. I now use the pin to "size" the inside diameter correctly before the final rolling "on the pin" with instrument lacquer.



    8.5 X 11 vellum is readilly available in art supply stores.
    It looks like frosted glass and comes in several colors beside white (clear). I got a pack to expariment wity making translucent wings and sails,and also windows. It's been setting in a drawer ever sense, of course. Funny, the glider in this weeks picture reminded me of it.
  6. Gil

    Gil Active Member


    The booring task of turning out three dozen of those tiny clamps has preoccupied my building time in the last day or two. Found that using the vinyl eraser on a cutting board does a great job of rolling tubes. Just start the tube with an eraser and mandrel, free roll between thumb and forefinger then place on cutting board and use the eraser to roll the tube tighter. Make sure the flap is facing away from the direction of the roll otherwise you'll do a quick unroll job. Using a finger to roll a tube on the eraser also works but it's more fun to "drive" the tube around the cutting board with the eraser. A pin mandrel can be used to roll to an inside diameter. Mount tube on the mandrel and then place tube and mandrel on an eraser surface. Use another eraser to roll the tube around the mandrel pin. Coat with a little glue and finish the roll with your fingers. Make sure you clean the mandrel afterward.

  7. Maurice

    Maurice Member

    Much muttering you might save if you use a knife edge along and very close to the edge of the paper to hold the edge of the paper firmly against the mandrel as you pass the first winding across the edge of the paper and blade.
    If that is tight when the blade is taken away, the roll can be rolled tightly without any need for additional rolling to tighten things up.
    Needs practice.
  8. jasco

    jasco Member

    Just to get back to the nitrate dope for a minute... I have a balsa and tissue model airplane that I built in 1984. Don't ask me how it survived that long! The covering was plain white tissue with nitrate dope. Over the last 22 years there has been significant yellowing of the covering. You may want to take that into consideration before using dope on your paper model. The model has been in a dark corner of the basement for about 15 years, so there hasn't been too much exposure to sunlight. As for rolling tubes...this is exactly the reason that I love this forum! I never thought of using erasers, pins, or vellum. In fact, I had given up on making small diameter tubes out of paper and had been using painted toothpicks for landing gear, guns, etc. Thanks for the tips!
  9. Maurice

    Maurice Member


    That's an interesting observation and I don't doubt it for a moment, but as always mileages do seem to vary.
    I've been using nitrocellulose lacquer as a timber finish on furniture for 25 years now and there has been a lot less colour change with it than with any other clear timber finish.

  10. cygielski

    cygielski Member

    Jasco, could it have been the paper itself that has yellowed over the years?
  11. mwangarch

    mwangarch New Member


    Just remember that nitrocellulose is guncotton dissolved in a solvent and can be (depending on the amount of nitration) very flammable.
  12. Gil

    Gil Active Member

    Good to remind everyone that nitrocellulose lacquer is very flammable and that a good deal of caution should be exercised when using it (Rauchen Verboten!).

    While on the subject of rolling tiny tubes I was wondering if anyone has tried using thin latex exam gloves yet. They should be ideal for the purpose.

  13. Gil

    Gil Active Member

    The latex exam gloves don't work all that well for free rolling (unless you want latex rolled up with the paper). They are good at keeping all sorts of toxic stuff off your skin and are worth having some around.

  14. wunwinglow

    wunwinglow Active Member

    Also, latex gloves can inhibit the cure of certain paints, glues etc. I'll get a list from work. We use a different type, although they are more expensive.

    Tim P
  15. Gil

    Gil Active Member


    Probably the Acrylonitrile type. Latex is an allegen to some people.

  16. Gil

    Gil Active Member

    Rolling A Long Tube

    Quick Update:

    Couldn't leave well enough alone as usual..., the following shows the result of a little thought, several trials and finally success. The technique doesn't use instrument lacquer in the rolling process. The roll is started by using the ruler in the picture as a clamp and edge for beginning the roll with a fold up along the rule edge (done by a putty knife). The formed angle is then rolled around a 0.0625 inch mandrel (~1.5mm). This takes some manipulation along the length of the mandrel until the roll is started and fairly uniform along the length of the mandrel (paper width is around 18 mm). a sponge rubber pad (an old mouse pad works well) is used to roll the tube into a uniform round tube. Don't worry about tightness just get the tube uniform around the mandrel. Dampen with water and work further to tighten the roll on the mandrel. Remove the tube from the mandrel and return to the rolling surface. Work the roll with the sponge to tighten the roll. Take your time and work the sponge along the length of the roll to maintain an even diameter. Once satisfied with the diameter of the tube apply thinned white glue to the length of the tube and continue rolling with the sponge. Set aside and let dry. Apply instrument lacquer for additional stiffness and strength. Almost forgot, the length of the long one is about 8 inches (21 cm) and is made from vellum tracing paper.


  17. Leif Oh

    Leif Oh Member

  18. Gil

    Gil Active Member

    Tube Forming

    Hi All,

    I've been preoccupied with developing the ignition wiring for the Wright Cyclone and went down several paths before messing about with the tiny tubes mentioned earlier in this thread. Suprisingly enough a new forming technique was discovered!

    Roll a small diameter tube that you can insert a slightly longer bare copper wire (24 AWG in the case shown here) and form it into the desired shape. Coat with instrument lacquer and set aside to dry. Make sure that the lacquer doesn't flow down the open ends of the tube in between the tube and the inserted copper wire. Remove the copper wire by gripping with a pair of needle nose pliers and holding the tube end between thumb and forefinger gingerly withdraw the copper wire. The completed radius will spring open some when the copper wire form is removed so take this into account when coiling the composite. Also the rolled flap may unbond and may need to be smoothed down and tacked down. This hasn't occured with any of those coated with lacquer. The two images are separate parts. The one on the left is being used to develop the ignition ring for the Cyclone.


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