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Building Tips and technical articles. => Building techniques => Topic started by: rob biddle on November 16, 2006, 03:33:00 AM
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Hi all,
I know this has been brought up before, but......
Which dope is which? ???
I believe that Nitrate is the non-shrinking dope and that butyrate is the shrinking type,No?
The reason that I ask is that the dope that I have become very accustomed to using is no longer in production. Bummer! :'(
It was just labelled "model aircraft Dope". Never stated whether or not it was butyrate or nitrate, but I assume it was nitrate.
Unfortunately, due to all of the hazmat rubbish, it appears that no one will import Brodak or Sig dope into Australia as the market is so small. The options are fairly limited.
There is one particular brand of nitrate available here that I am loathe to use as it has caused me huge problems with thinner compatability and the company concerned don't make a thinner to suit it. n1
Which means the only alternative is Randolph aircraft dope, which a few of the guys here have used with a fair bit of success.
The added bonus of using Randolph dope is that it's available by the gallon! ;D
Any thoughts before I "commit" to a gallon of Randolph would be greatly appreciated.
Thanks in advance, Rob.
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Hi Rob,
It gets more confusing since both Notrate and Butyrate are available as tautening (shrink) or non-tautening types.
Randolph is a great, and perfectly acceptable, dope for us to use. Brodak's dope (at least when they started making it) is Randolph based.
I use Randolph non-tautening tinted Nitrate (when I can get it) for all the substrate on my builds. Then go to the shrinking type of butyrate on the open bays and non-shrinking on everything else after the silkspan is attached,
Nitrate is not hot fuel proof, and you do not use Nitrate after you have used butyrate. It will attack the butyrate.
Bill <><
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Which means the only alternative is Randolph aircraft dope, which a few of the guys here have used with a fair bit of success.
The added bonus of using Randolph dope is that it's available by the gallon! ;D
Any thoughts before I "commit" to a gallon of Randolph would be greatly appreciated.
Thanks in advance, Rob.
Rob,
I just got an order of Randolph from Aircraft Spruce yesterday. I got quarts of both tautning and non tautning nitrate and butyrate dopes, and both types of thinners
restocking my paint cabinet.Easy folks to deal with too! Just a FYI, make your order with quarts v/s a gallon can save you the 20 buck hazmat additional fee. My shipping was only 7.71(Fedex) total for 5 quarts. Each can is carefully wrapped and taped, so its not obvious that it could be gallons of hazardous stuff....
Richard
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Thanks Gents,
Looks like I need 4 types of dope instead of one! **) ???
Hopefully I should get down to one of the aircraft paint supply places in the next few weeks. ( about 120 miles from here)
Three that I know of stock Randolph dopes so I will quiz them all on cost vs quantity etc.
Should be an interesting day out if anything.
Thanks again, Rob.
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I only use Butyrate dope on everything!
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I only use Butyrate dope on everything!
Hi Rob,
Like Sparky says, you can get by with only Butyrate (but I hope Sparky uses shrink and non-shrink). It's all personal preferences! y1
Bill <><
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I only use shrink type.
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I use Brodak Butyrate through out, then auto clear top coat.
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Hi Folks,
Thanks again for the replies.
I probably should have worked out what I really needed to know by letting you guys know how I have been finishing my models. n~
I generally use silkspan on open bays, a couple of coats of dope on sheeted areas (fuselage) with dope and talc (or corn starch) for grain filler. After this I generally go to grey primer (acrylic), painted with either enamel or 2-pack base coat. Final top coat is 2-pack polyurethane clear.
Nowdays I use the one type of thinner throughout to try to promote better "bonding" between the different substrates.
I would love to start painting with coloured butyrate but it is unavailable here. :'(
Guess I really need to know which type of dope would be best to use basically as a grain and tissue sealer that will be happy with grey acrylic primer and not cause the silkspan to turn wings into a starved horse?
Thanks again, Rob.
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Rob,
The "starved horse syndrome" you describe has more to do with how the silkspan is applied, rather than shrink/noshrink dope. Silkspan covering (and silk as well) has a 'grain'. That is, if you take a piece and tear it going one direction, and a second tear 90 degrees from the first, you'll find: one tear will not tear straight, that is, the tear will wander a zig-zag (or curvy ) path across the paper. Tearing at 90 degrees to that tear you'll likely find a relatively straight tear. You apply the paper with the direction of the straight tear (the grain) going from wing root to wing tip.
Try it! b1
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What Ward says is very true. In my observations, though, the typae and amount of dope applied cancause contiinues shrinkage to all surfaces. I have not tried Brodak Clear butyrate (although I have used Randolph's. Sig Supercoat Clear will shrink a ton. That is great for getting a tight covering job over open bays, but I don't want it to keep on shrinking over the wood areas.
To each his own, and you can develope your own methods that work. Mine just happenes to be a nitrate base, non-tautening, and I can use anything over it!
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, then auto clear top coat.
"AUTO CLEAR TOP COAT?" n~ Hummmmm? That leaves an amazing amount of information to deal with, doesn't it.
Such as:
Which brands of clear coat..or which thinner by that name brand is best used with a certain brand of dope....can make or break any beautiful dope finish...almost----INSTANTLY?
Of equal importance is: the temp. of both the room and the paint product...the humidity of the room. Also what ratio of thinner to clear coat etc. etc.
Just about the time you think you KNOW ALL ABOUT PAINTING!
THEN SH^ %^ ~^
and time to remind ourselves...."We are truly only as good as our last paint job!"
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Dupont Nason 2 part auto clear. No thinner. Wet sand & buff out.
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Thanks Guys,
Now days I am using 2- pack base coat/ clear coat, as coloured dopes aren't readily available in Australia. SH^
I guess the market is too small to justify going through all of the hazmat red tape and bull dust.
Reasonable results have been had using Dulux rattle can enamels with Sikkens or Concept 2-pack clear for extra fuel proofing. The only drama is that the rattle can paint is quite thin and a bit hard to spray "dry" to get sharp lines as it tends to "bleed" under the tape.
I have organised for some non-shrinking Randolph butyrate and will build a trainer for my kids and maybe a quick .15 sized "sport flyer" to experiment with before I move onto the Brodak Nobler. ;D
As already pointed out, when I think I know everything about paint I find out by accident that I really know nothing! **)
Thanks again, Rob.