Nitrate Dope

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

  1. Gil

    Gil Active Member

    Hello All,

    I think we've all noticed that some of the builds have used Nitrate Dope as a stabilizing coat for printed paper models. Curiosity got the best of me and I purchased a pint can of Sig Nitrate Dope. Research revealed that another name for it is instrument lacquer used on musical instruments. Nitrate dope does not shrink or tauten aircraft fabric coverings as does butyrate dope.

    I coated both sides of printed light cardstock to see what effects if any it would have. It is very clear and applies easily right out of the can although a small amount of thinning might facilitate flow properties. It had absolutely no effect on color nor on the visual look of the paper. Touch feel of the paper was noticeably "silkier". The paper did take on a sort of plastic film quality allowing glue stains to be cleaned up easily without untoward effects on the card stock. The cardstock was noticeably easier to sand with the fuzz factor greatly reduced.

    That's the extent of observed effects so far. Like to hear from anyone else who's tried it.

  2. Maurice

    Maurice Member


    You are mistaken.
    Clear nitrate (or nitrocellulose) dope most certainly does shrink on drying and that property is used by the aeromodellers amongst us to taughten our tissue coverings. It was it's extreme flammability that led to the development of the alternative butyrate dope.
    I am not sure whether the nitrocellulose lacquers which are used by instrument makers (and the more enlightened cabinet makers amongst us :D) to provide a hard, smooth, durable and very clear finish to our timber is exactly the same formulation.
    I've never tried swapping their uses and whilst I've seen the distorting effects of nitrate dope on paper and card I've never tried using nitrocellulose lacquers on paper products.

  3. gera

    gera Member

    Maurice you are right.........The only reason I used Dope on my wood stick models was to get that paper covering to tighten and take shape of the structure. It shrinks great....... :)
  4. Gil

    Gil Active Member

    Sorry, I stand corrected. Nitrtate dope used in conjunction with modern aircraft fabric (ceconite) is non-tautening which can cause some confusion. Again I wasn't asking whether you use it on balsa models the question was whether you've used it on paper as have many of the European modelers...,


    P.S. They still use nitrocellulose lacquer for fine stringed instruments.
  5. gera

    gera Member

    No sweat Gil...I am presently trying a mixture of liquids which seem to work very nice on "printed paper" with a matt finish. If my test comes out OK and it does not mess up the paper I will "tell" secret formula.... :lol: :eek: :eek:....
    The best thing I have tried so far, to "Protect" the colors of the print is a "Wood varnish".....(I have the bottle at home, so right now I don´t remember the name).....The model using it has over 4 months, and some sunlight shines on it daily and so far no visible discoloring....
  6. Gil

    Gil Active Member


    I've tried the following so far;

    o Sanding sealer (lacquer based)
    o Laquer
    o Shellac
    o Dissolved Stryofoam in Toluene
    o Nitrate Dope

    The nitrate dope seems to yield the hardest surface with lacquer coming in a very close second. Sun aging is another concern which hasn't been addressed in any of my trials. You're certainly in the right area of the World to do a Sun test though. I've found the acrylics to be a little to soft or in sanding terms "gummy". The nitrate leaves the paper stiff and machineable which none of the others approach as well save the styrofoam dope. One of the tests is the ability to cut fine slivers of treated paper without the paper disintegrating into fuzz. Nitrate dope seems to excell in this area which implies that it strengthens the paper enough to allow fine detail cuts to be made.

    I'm very interested in hearing more about your "secret formula"....,

    Best regards, Gil
  7. wunwinglow

    wunwinglow Active Member

    Jeez, Gil, I hope your workshop is well ventilated!! Either that, or you can hold your breath like a whale...

    Tim P
  8. Gil

    Gil Active Member


    Plenty of ventilation required for any of these except maybe the shellacs which is thinned with grain alcohol...,

    Best Regards, Gil
  9. wunwinglow

    wunwinglow Active Member

    HeHeHe! Hic! Just remember to carry a feather duster so you can do something useful while you are floating about the ceiling!!

    Seriously, I remember (just...) getting pulled over by one of the boys in blue as he thought my motorcycling was a bit erratic. (This was a VERY long time ago!) I HONESTLY hadn't touched a drop, just thought it was 'flu or something, but a few days later noticed the filter pack on my workshop spray mask wasn't seated properly. I'd been in the spray shop for several hours the day I got pulled over.....

    It creeps up on you. Please, keep the windows open, and no naked lights!

    Interesting experiments though, as always.

    Tim P
  10. Maurice

    Maurice Member


    Obviously you hadn't asked about it's use on balsa models. The hope was that by drawing attention to it's intended use you might be able to understand the potential problems and, even if you didn't, others might.
    You seem not to have noticed that I also wrote "I've seen the distorting effects of nitrate dope on paper and card". Not too much point in asking if you don't read the answer.
    I have no idea exactly what the Europeans are using but I wish them luck if it really is nitrate dope.
    Ceconite requires the use of a non-tautening nitrate dope which is presumably a slightly different formulation.

  11. Leif Oh

    Leif Oh Member

    A little less acerbity (I distinctly remember seeing a courteous "Sorry, I stand corrected") would seem to be more productive to this important and interesting discussion.

    On the issue at hand, I would be most interested to learn whether there is a clear shellac available. I remember using shellac on a 2 meter RC glider a long time ago, just to get away from using stuff with obnoxious fumes.

    The procedure included buying brown flakes of dried bugs (yes, it really is bugs, if I remember correctly), and dissolving them in denaturated alcohol. The varnish was very nice to use, although quite brown and therefore not suitable for paper models. It didn't sand too well either.

    If there really is a clear variant of shellac, I want it! It wouldn't distort paper like clear acrylic does, is that right, Gil?

    The way I'm going to use acrylic from now on is to prevarnish every part, on the sheet and before cutting them out, in the hope that all distortion will be done with there and then. It is much easier to flatten a single part, or a sheet (if necessary by ironing it from the backside), than the covering on a finished model!

    Prevarnishing parts parts with clear acrylic should enable final coats of acrylic to subassemblies and the finished models, without resulting in further distortions.

  12. Gil

    Gil Active Member

    Thanks Leif for explaining the rationale behind the application...,

    The following traits are desirable:

    o Strengthens the paper allowing finer detail to be cut
    o Reduces or eliminates paper fuzz from sanding
    o Low to zero planar distortion
    o Low to zero print quality effects
    o Stabilize the paper protecting it from water based
    glue, paint and filler application
    o Safe to use

    I have tried a clear shellac manufactured by BullsEye and it does fufill the requirements. I would prefer that it yield a harder surface though but compared to the others it is enviromentally safe. The nitrocellulose and lacquers yield the best overall qualities and I've found that surface distortion doesn't seem to be a problem.

    Coating only the print side still allows for moist forming methods if they are prefered otherwise both sides are coated reducing or elimnating the need to use solvent based glues. Another important benefit is that water based fillers can be used without worrying about the "sags".

    Best regards, Gil
  13. Maurice

    Maurice Member


    I agree with your assessment, the "Sorry, I stand corrected" failed to mask the acerbity that followed.

    On the issue at hand, suffice that some will think twice before using nitrate dope. It's full effects are not always immediate.

  14. bfam4t6

    bfam4t6 Member

    This is an interesting topic. I myself have some dope for balsa models. I just looked and the label simply says "lite coat clear dope" so I'm not sure as to whether it is nitrate or not.

    As far as Maurices statement about the dope being used to shrink, that may well be. However, I was taught to moisten the tissue on a balsa model and let it dry before doping. This makes the tissue very taught, and then I apply dope to seal and strengthen it. Since the tissue is already shrunken when I apply the dope, I cannot say for certain whether or not the dope I use shrinks and tightens it even more.

    Also, Gil, you mentioned that the glue stains were more easily cleaned up after the paper was treated. You may have answered my question in one of your posts and I simply missed it, in which case please forgive me, but how else is glueing effected? You said the paper almost became like a plastic film, so if I were to use tacky glue on the paper, would it peel apart as it would if i tried to glue aluminum to aluminum or plastic to plastic? I am just thinking that a smooth sealed surface would probably not soak up the glue as well as untreated paper. Also, any effects on drying times? I am curious to see the effects of this and I am also curious to learn how your secret "potion" turns out Gera.
  15. Gil

    Gil Active Member


    You're right about the glue not penetrating the coated surface. Whether this is good or bad depends on what you want to do. I like the sealed surface as positioning becomes a lot easier. If the parts have to be pulled apart you can without the paper separating into layers (disaster time usually). I havn't experienced any problems with adhesion once the glue is dry as the paper will fail before the glue joint does. All in all it's my opinion that it turns the building experience into one where you can actually concentrate on building and enjoy the experience.

    Best regards, Gil
  16. Gil

    Gil Active Member

    Small Diamter Tubes & Instrument Lacquer


    I've been taking time to better understand the making of small diameter (around 1 mm) tubes. Experiments led down to selecting 25% rag vellum tracing paper. It's tough and "works" well. Vinyl erasers allows the tubes to formed fairly quickly after using needles in a pin vise to obtain the intial curl. The roll is then put between two vinyl erasers and rolled till tight. Gluing the roll took some time to come up with a soulution. The one that worked better than all others was dipping the rolled tube on a pin vise needle into nitrate dope and then spinning it tight between the thumb and forefinger until the dope loses it's tack. The finished part looks like white styrene and has many of that materials mechanical properties. Another nice property is the ability to make thin wall to fairly thick wall tubes and the dope doesn't affect the print quality. I can see why many of the modelers in Europe are using it. The resulting tubes are strong, edge clean and integrate well into card modeling.

    Best regards, Gil
  17. Maurice

    Maurice Member


    Glad you've found a use for your pint of Sig. :D
    Not a use where the dope could cause any flat surfaces to distort either.
    Can you clarify what printing you had on the paper please and give an estimate of the maximum length you think could be rolled at, say, 1mm diam.
    Also, you earlier mentioned experiments with lacquer but that term covers a mutitude of brews so what type were you using?

  18. barry

    barry Active Member

    small diameter tubes


    You always set me off when you do articles on tubes and the fact I found rolling the barrels for the pompoms I was trying to make very difficult. I was trying 80gm notepaper and when the phone rang I ended up with original needle mandrel stuck behind the roll I was trying to make and idly spun it in fingers while answering afterwards I realised the tube I had made was the tightest I had ever managed. Afterwards you cut off a piece of paper already moulded for a tight roll round a wire barrel. The centre of the roll looks about 1 mm diameter.

    I suppose the pin turns into the equivalent of a rolling mill.

  19. Gil

    Gil Active Member


    You came to mind when one of the rolls went askew some and ended up the perfect taper for a naval gun barrel. Stanchions are another item that rolls easily. The pin you have pictured is similar to the one I've been using except the head was snipped off o fit into the pin vise. The trick is to get the roll started first with a more manageable mandrel size (larger) against a vinyl eraser. The roll is then tightened by free rolling between thumb and forefinger before mounting on the pin mandrel for final tightening. One important point bears repeating, putting the free rolled tube between two vinyl erasers and using them instead of your fingers to further tighten the roll. Note that the roll must be rolled in the direction such that it will not come undone. This technique works very well and is worth the price of a few erasers which also have excellent chemical resistance. Again, it was SIG Nitrate Dope that was used for the application with lengths varying from 1 mm to over 25 mm. The other name for Nitrate Dope is Instrument Lacquer (Nitrocellulose Lacquer) which can be found at shops catering to luthiers. It is one of the hardest of all the clear finishes used in this trade giving some indication as to it's ability to pentrate and strengthen paper...,

    Warmest regards, Gil
  20. barry

    barry Active Member


    hi gil

    Just tried your rubber trick and does indeed tighten the roll even more the interior diameter of the roll is now about .5mm. I tried to take a pic but it's a bit dim the outer diameter is 3mm. If you look hard the black dot in the centre is the width of the hole left. This is great for rolling masts as you end up with a solid tube to work with and I shall definately use this on Hood for the aft tripod.


Share This Page