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Post  SuperDave on Sun Aug 21, 2011 11:13 am

To me the biggest obstacle to nitro flying is the apparent disappearance of COLORED fuel-proof "dope". For you "newbs" DOPE is a paint-like substance applied to the external non-metal surfaces of aircraft both full-scale and model.

In nitro flying plain DOPE is quickly destroyed by the nitro exhaust UNLESS it is "fuel-proof". The only fuel-proof DOPE availabe today only comes in CLEAR. The present alternaive to furl-proof DOPE is synthetic coverings like Mono-coat and similar,
The weight of synthetic coverings precludes their use in micro-flight.

I'd appreciate input and would welcome any discussion about this predicament.

TXS, SuperDave
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Post  gcb on Sun Aug 21, 2011 11:51 am

There are basicly two kinds of dope, Nitrate and Butyrate.

Nitrate dries faster, is GREAT for adhering coverings, but is NOT fuel proof.

Butyrate dries slower, but is somewhat fuel proof. It is generally accepted that it is fuel proof up to about 15% nitro fuel. Many modelers top coat the color with final coats of automotive finishes that are totally fuel proof. For 1/2A purposes (higher nitro), just wipe up your spills before it softend the Butyrate.

THEY ARE NOT COMPATIBLE, that is, you can not cover butyrate with nitrate because it dries faster and will trap the solvents between the two and cause the nitrate to come off in sheets. You can, however use nitrate for initial and fill coats, then use colored butyrate.

Yes, butyrate does come in colors. Some sources are SIG, Brodaks, and perhaps Randolphs. You can get it in 4oz. jars, pints, quarts, and gallons.

There are iron-ons lighter than Moneycote, but I don't use them. You can do a search for brands and sources.

Hope this helps someone.
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Post  MiniatureAircraftFactory on Sun Aug 21, 2011 12:56 pm

Nitrate dope and Butyrate dope can dry at the same speed , our formulas ( StarSpan ) use exactly the same solvent base for both types ( but still nitrate cant be painted on butyrate! )

You can only paint butyrate over nitrate , not the other way round ( but you can get away with it sometimes ! )

Nitrate is fuelproof for straight methanol castor fuel , it is ok with 5% nitro fuel but no more is safe ( most times 16% nitro will be ine unless you soak a doped surface in it) , 1/2a glow fuels melt it , with diesel engines the usual fuels ( not all racing formulas ) are fine on nitrate doped surfaces

Butyrate dope is fuelproof for nitro and diesel based fuels

At the minute we only manufacture clear dopes, sanding sealer etc but in the past We have done batches of coloured dope in both nitrate and butyrate cellulose formulas called StarLac ,

i was thinking about doing it again the other day in limited amounts

We just didnt have time to grind the pigments to produce the range of colours i wanted we had about 40 colours available ( each takes about a week to grind the pigments in a ball mill ) ,

if we produce some again we will make a limited range of colours ( at first )

I never understood why people dont use coloured tissue , its lighter , you can get a full range of colours in the StarSpan tissue so no need for coloured dope

I use coloured films on most of my models even though there heavier ,simply because i tend to put them on display at shows and people poke at them....... so the tissue wouldnt last so long when kids get the models



Its a great thing running a chemical factory when you make models, you can make anything you need

Its a strange thing to have but i have videos of mixing nitrate dopes on youtube!
https://www.youtube.com/watch?v=9p7rdf0IjcE


Last edited by MiniatureAircraftFactory on Mon Aug 22, 2011 7:05 am; edited 1 time in total
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Post  SuperDave on Sun Aug 21, 2011 1:26 pm

Thank you for the tips, MAF & gcb.

Good info for everyone to know.

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Post  SuperDave on Sun Aug 21, 2011 1:37 pm

One of my anticipated "builds" is a Guillow's WWI Thomas Morse Scout which has a checkerboard pattern on the nose. Since the "checks" are about 1/2" square doing them in colored silk span would be a task not undo able but difficult. "Doping" them on would seem a better alternative, IMO, but I'm open top suggestions.

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Post  nitroairplane on Sun Aug 21, 2011 5:36 pm

I use cellulose dopes
And recently I used a thing called eze dope it is neat odourless and can be safely used indoors it Is fuelproof but i only got a chancle to use it on a rubber peered cub but it did a great job.
But coloured tissue is your best bet and it looks scale for ww1 planes.
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Post  MiniatureAircraftFactory on Mon Aug 22, 2011 6:44 am

The ezee dope isnt realy a dope they just call it that , its the same as waterbased floor varnish you can get from the diy shops , theres also another `waterbased dope` being sold as well that is just watered down PVA!

The term dope is a technical term used for a solvent solution of a plastic , the waterbased product is a dispersion ( little beads of plastic suspended in the water) not a solution of the plastic so is not technicaly a dope

We have done a waterbased one on and off since 1994 but most people prefer a decent cellulose dope than the waterbased ones so we dont always bother with making the waterbased
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Post  nitroairplane on Mon Aug 22, 2011 7:20 am

MiniatureAircraftFactory wrote:The ezee dope isnt realy a dope they just call it that , its the same as waterbased floor varnish you can get from the diy shops , theres also another `waterbased dope` being sold as well that is just watered down PVA!

The term dope is a technical term used for a solvent solution of a plastic , the waterbased product is a dispersion ( little beads of plastic suspended in the water) not a solution of the plastic so is not technicaly a dope

We have done a waterbased one on and off since 1994 but most people prefer a decent cellulose dope than the waterbased ones so we dont always bother with making the waterbased
Yeah eze dope is more like a wax.
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Post  SuperDave on Mon Aug 22, 2011 9:49 am

My original thread has been pulled of course and some of the later information isn't really relevant to the situation that I decribed.

I'd like us to been discussing colored light weight nitro fuel-proof coatings for micro-flight, please.

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Post  nitroairplane on Mon Aug 22, 2011 11:12 am

Ok coloured tissue or silk then cellulose dope is the perfect combination.


Last edited by nitroairplane on Tue Sep 06, 2011 3:46 pm; edited 1 time in total
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Post  andrew on Mon Aug 22, 2011 2:01 pm

SuperDave wrote:
I'd like us to been discussing colored light weight nitro fuel-proof coatings for micro-flight, please.
SuperDave

Since you're looking for a fuel-proof coating, you're pretty well locked into butyrate dope should you choose that route. It is not necessary to prep with nitrate dope; I've covered many planes with butyrate dope only with good results. One topic that was not covered (unless I missed it) was high-shrink vs low-shrink dope. Generally for open areas (the Morse Scout is essentially all open), we would use a high shrink dope to ensure the covering is tight and without wrinkles; on solid areas of the model, use low-shrink. Lightly built models can sometimes be warped if high-shrink dope is used throughout. If the model is light weight, one technique employed is to apply the covering with high-shrink to tighten and remove wrinkles and then follow up subsequent coats with low-shrink. Early on in my modeling career, I ruined a fuselage by using only high-shrink on the 3/32" sides --- the next afternoon when I checked it, the sides were curved like a pretzle.

The Guillow's Morse Scout is a small plane and with the exception of the roundels, rudder stripes and cowl, it is all olive drab. My inclination would be to use Olive drab tissue to cover the entire aircraft, then add the roundels and identification stripes with a different color. Applying tissue over tissue can be difficult and at times frustrating, simply because tissue is light and has a tendency to fold over itself. One way around this is to build a small frame and make swatches of pre-shrunk tissue --- once shrunk and doped, the tissue can be easily cut and it will be stiff enough to handle. Cut a section to the shape needed (it's already shrunk so it won't pull away from adjacent pieces) and apply --- dope has an interesting and useful property in that it will re-dissolve when thinner is applied. Place the pre-doped sections on the plane, then paint with thinner. The dope will dissolve and fully adhere the tissue to the underlying tissue. You can build complete roundels on the frame before applying to the wings. Your cowl will be more difficult, but Esaki to the rescue. You can now get checkerboard tissue (who would'a thought) in red/white 7/16" squares (http://www.darehobby.com/accessories/tissue02.htm) --- frame it up, cut to shape and apply with thinner. If you're worried about show thru, use white under the colors. DARE Hobby also carries olive drab tissue.

For such a small model, silk is heavy and will require more filling and color to complete the scheme; colored tissue would be my choice for this plane.

Brodak does not indicate if their clear butyrate is high or low shrink; SIG does sell both versions. Brodak is a specially formulated product from Randolph with higher solids than used in the full-scale market. I generally buy my Randolph clear through Aircraft Spruce --- purchased in quarts, there is no hazmat fee and it's a little over half the price of Brodak, plus you can specify tautening (high shrink) or non-tautening.

andrew


Last edited by andrew on Mon Aug 22, 2011 2:12 pm; edited 1 time in total (Reason for editing : Added information)
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Post  SuperDave on Mon Aug 22, 2011 4:23 pm

Interesting , Andrew. Thank you!

I'll try your ideas on my Thomas Morse Scout. To my knowledge the most commonly used Allied combat aircraft of WWI.

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Post  ThermalSniffer on Tue Sep 06, 2011 3:39 pm

I feel I must make mention of Klass Kote epoxy paint here. An epoxy paint is, for all intents and purposes, completely inert against even high nitro fuels. A light airbrushing of clear Klass Kote on top of a doped finish is the perfect solution for those who don't want to colour their finish. For those who do want colour there are plenty of premixed colours to choose from especially if you enjoy scale subjects. The owners are also content to mix colours for customers. Not as simple to apply as butyrate dope but far superior in this application as a fuel proof top coat. I've read about a couple of free flighters and even an enlightened rc guy who are using this stuff. I would use this stuff if you are covering in tissue or silk and where fuels with up to 60% nitro might contact the surface.

Regarding colour dopes, in the UK at least, I am able to buy HMG brand dopes that come in various colours. I've not had a need to use them yet and the bottle does not say if they are butyrate or nitrate.
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