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Using Butyrate dope ?

Old 12-23-2014, 06:13 AM
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TampaRC
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Default Using Butyrate dope ?

Could anyone here help me with the correct application of dope please? I asked this same question of Brodak from whom I was going buy all the dope and supplies, but he refused to help me and instead told me to buy a book about it.

All I want to do is paint a couple of 1/2a profiles with flat sheet wings.

I am not clear on how to use sanding sealer, and I once saw that you first paint all the wood with clear ????? Confused. Also do the products need to be thinnned if applying with a brush?

Is there another supplier inste
ad of Brodak? Any help would be appreciated.
Matt
Old 12-23-2014, 06:34 AM
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Sanding sealer is a primer. If your wanting a stunt ship finish you will need it. on a flat balsa wing 1/2a, at least the one I built when I was a kid, I just wanted to fuel proof it. You can use clear as the base coat, or the color. You just need to sand it lightly after the first and second coat gets good and dry. even wet sand it after the second coat for a really good finish. You probably do need to thin the dope with dope thinner. Then a third coat out to finish out your model. And alternative I've used for dope in the last several years is elmers white glue mixed with alcohol. its way cheaper than dope, and dont smell as good . But fuel proofs the model. I've mixed food coloring with mixed rresults. normally I just use it as clear. I use it the same way. two coats sanded and a final. I call my mixture "synthetic dope" I originally came up with it to use on foam. Worked so well I use it on anything I need fuel proofed now.
Old 12-23-2014, 06:40 AM
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Sure thing! Dope isn't hard at all, been working with it since the mid 1950's. Basically, sanding sealer is nothing more than clear with talcum powder mixed in - the powder helps fill in the holes/grain/etc. ALL my experience is with brushing dope, so here goes:

Now, I'm no expert on finishes but, if it were me on 1/2A profiles, AND THEY HAD TO FLY, I would mix a couple ounces of clear with a tsp of talcum powder, thin it by 1/3 (2 oz dope, about 3/4 oz thinner) and brush it on. Once dry, I'd sand lightly with 150-200 grit sandpaper. This is done until you're happy with the surface - usually a couple coats does it. Then I put on a 50/50 thinned coat (or maybe 2 - but a 1/2A would probably take just one) of clear. Once that was dry and sanded the final color coat could go on - I usually thin my color just a bit to help spread it. One coat usually does it, sometimes a 2nd - depending on color.

Then, my planes fly. I've got C/L planes that date back to the mid 1960's still in the air with their original dope & silkspan covering, so the method seems to work just fine.

Yeah, Brodak & SIG are the two best dopes I've had experience with. There are probably others out there but I haven't used them.

Good luck with your planes. Post some pics when they're done.
Old 12-23-2014, 08:34 AM
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I had forgot about the talcum powder. Been a long time since I used dope. I recall also that we used to put in a cap full of castor oil in the dope too. That kept the tissue pliable instead of brittle.
Old 12-23-2014, 09:12 AM
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TampaRC
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Bob and Dave......

Bob what is the ratio of alcohol to elmer's glue is best ?

Dave, it sounds like instead of buying sanding sealer, I just make my own with talcum.....same deal?

aLL THIS IS SUPER INFO !!!!

Matt
Old 12-23-2014, 11:16 AM
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Yup, same thing, and you don't have to buy another bottle to store later. Now, it's been DECADES since I bought sanding sealer but, as I remember, every new bottle had settled so there was something like 1/8" (or less) layer of powder in the bottom of a 4-oz bottle. That's not much powder.

Hey Bob, I've heard of castor oil in the dope but have never tried it. It DOES make perfect sense, however. That's also an interesting idea with the elmers & alcohol - gonna have to try it one day. All my C/L planes (7 are flying) are dope & silkspan (4 - more than 40 yrs old) or dope & SIG Koverall (3 - all 20+ yrs old), almost all (9, of which 6 are 35+ yrs old) my RC planes are monokote.
Old 12-23-2014, 12:29 PM
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I usually start with 50/50. just mix it to the viscosity you like. Goes on like dope, feels like dope. Easy cleanup.
Originally Posted by TampaRC View Post
Bob and Dave......

Bob what is the ratio of alcohol to elmer's glue is best ?

Dave, it sounds like instead of buying sanding sealer, I just make my own with talcum.....same deal?

aLL THIS IS SUPER INFO !!!!

Matt
Old 12-23-2014, 03:50 PM
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Generally dope in 8 oz. jars is ready to use with a brush. If you use a sprayer it will need to be thinned. Larger quantities in cans, pints, quarts, and gallons usually need to be thinned before use. Unless you want to delve into dopes and thinners, use all the same brand. I have used both SIG and Brodak and both work fine.

George
Old 12-23-2014, 09:11 PM
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mikeainia
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Bob - what kind of alcohol? Do you use methanol, straight isopropyl, does it matter?
Old 12-24-2014, 06:28 AM
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Originally Posted by mikeainia View Post
Bob - what kind of alcohol? Do you use methanol, straight isopropyl, does it matter?
I use the cheapest rubbing alcohol I can find. It just evaporates and leaves the glue behind. Super thin and smooth though. I've even used it on tissue with good results.
Old 12-27-2014, 02:39 PM
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Originally Posted by Bob Mears View Post
I use the cheapest rubbing alcohol I can find. It just evaporates and leaves the glue behind. Super thin and smooth though. I've even used it on tissue with good results.
Bob,
Since rubbing alcohol is mostly water (unless you get the more expensive kind), have you tried thinning with just water? Does the alcohol make it sandable?

George
Old 12-27-2014, 05:42 PM
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Yes. I originally used white glue and water on foam combat ships back before we had plastic covering. I covered the foam with tissue and used white glue and water to shrink and seal it. The down side with the water is that it would just bead up on the foam. It would work, but not very well. When I started using the alcohol it went on like dope. Really smooth and no beading up. I still use it today instead of the dope since I'm always using foam now days.
Originally Posted by gcb View Post
Bob,
Since rubbing alcohol is mostly water (unless you get the more expensive kind), have you tried thinning with just water? Does the alcohol make it sandable?

George
Old 12-27-2014, 08:36 PM
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I tried some of the white glue mixture on a piece of foam today, after a day or so drying. Straight nitro dissolved right through into the blue foam that I used. I guess it isn't really fuelproof. It was a fairly good finish, and applied easily. I guess I wouldn't be using 100% nitro. I am trying to get a new method for painting too, now that no VOC paint is the norm. I'll keep searching, and trying with the glue thing. I found some clear glue that smells a bit like the white glue to try.
Old 12-27-2014, 10:16 PM
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When it comes to using dope, I buy clear by the gallon with a gallon of dope thinner. There is a aircraft supply right next to the airport in Fort Worth. It's a lot cheaper by the gallon. ($36.00/gal vs $8.00/ 4oz)

I first brush on two coats of clear full strength. When dry, sand with 220 sand paper just to get rid of the rough surface. This seals the wood and silk so that the thinned sanding sealer doesn't just soak into the wood and cause a lot of unnecessary weight.

Then I mix my dope 50/50 with dope thinner and add talc until I get the right consistency to brush. After 2 coats and dry over night, sand again with 220. I sand most all the sanding sealer off. You can see the white talc in the pores of the wood. Another coat of sanding sealer may be applied if necessary. Once I and satisfied with the surface of the wood and silk, I apply another coat of 50/50 clear and let dry over night.

I then thin my color dope to a nice brushing consistency. All my color dope is NON-TAUNTENING !!! Each coat of color dope gets thinned more and more until my last coat is mostly thinner. This allows the dope to flow out very nicely with no brush marks.

You can apply one last coat of 50/50 clear dope to add a nice gloss to your finish to you plane.

I've done this since the late 50's.

HINT: If you are going to use a yellow color, apply a base coat of white first. Yellow doesn't cover very well and will take a million coats to make it opaque. White seems to have a much larger pigment and covers really well.

HINT: Always start with your lightest colors. Don't try to apply yellow over blue or sky blue over black in other words.

HINT: If you use vanilla masking tape to separate your colors, always brush clear dope over the edge of the tape to keep the color dope from seeping under the edge of the tape.

HINT: If you add Castor Oil, just a teaspoon per quart is sufficient. Use Medical grade Castor Oil from the drug store.

HINT: After you remove your tape, you will have a ridge form. Wet sand with 400 or 600 grit wet or dry paper. Then add a coat of clear to the whole plane.

Good Luck
Frank
Old 12-28-2014, 07:42 AM
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I've never tried 100% nitro over the white glue to see if it would be that fuel proof. The most nitro I've ever used was 25% Plus I didn't mention I guess, is that I did put on several coats of the alcohol and glue mix. Back in the dope days the rule of thumb was 7 coats before the place was finished. I normally do 5 coats of the alcohol and water.

Originally Posted by aspeed View Post
I tried some of the white glue mixture on a piece of foam today, after a day or so drying. Straight nitro dissolved right through into the blue foam that I used. I guess it isn't really fuelproof. It was a fairly good finish, and applied easily. I guess I wouldn't be using 100% nitro. I am trying to get a new method for painting too, now that no VOC paint is the norm. I'll keep searching, and trying with the glue thing. I found some clear glue that smells a bit like the white glue to try.
Old 12-28-2014, 11:24 AM
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I did three light coats of the white glue mix. It does dry fast, and I will try using it a bit on wood, and maybe even silkspan some day. It is very hard to replace the old Hobbypoxy paints and even dope now. They are very expensive, and the planes are getting bigger. Not really mine. Any water based paint is dissolved by methanol that I have found, and enamels and laquer don't normally work either. Some urethanes, polyurethanes maybe, but I can't seem to find any coloured ones. There is supposed to be some Glidden porch and floor polyurethane paint, but I can't seem to find it here or Detroit, or even dope. It would be nice to just lay down thin fiberglass cloth or silkspan on foam or balsa, seal and colour a plane with one paint like epoxies or dope just to save weight. Looks like the space age turned into the tree hugger age.
Old 12-28-2014, 09:13 PM
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Nelson Hobby Paint is water based and fuel proof.

http://www.nelsonhobby.com/hobby_paint.php

I posted a detailed review of the paint on RCgroups.
Old 12-29-2014, 07:34 PM
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I didn't know it was water based. The clear is a bit pricey, but not really too bad I guess.
Old 11-01-2015, 04:14 PM
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It really is a very good technique for finishing. I did that on a C/L P-51 in 1988, and got very good results.

Ed
Old 11-02-2015, 07:03 AM
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Aerogloss has Balsa filler and Sanding sealer Balsa filler has more solids (talcum) to fill more deeper wood pores with less usage. But as posted above I still use 3 coats and sand in between and at the end I get a nice base to paint over.
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Old 11-03-2015, 12:47 PM
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If you're just fuel proofing sheet balsa planes to fly and bash you can use rustoleum solid products, no metal or flat finishes. They will work well on planes that are not long for this world. However you will not develop skills necessary for quality dope finishes. It all depends on application.
Old 11-03-2015, 11:57 PM
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Bob J and Clean
(Hi, Clean, it's been a while. Good to see you again!.)
(Bob, any further word on the K&B .28 scheduling?)

One thing I think I noticed missing so far ... how much nitro are we talking about? Nitro is an extreme solvent ...

Butyrates stand up pretty well to 5% nitro fuels, in my experience. 10% gets iffy, moreso if raw fuel sits on the model. With luck, a spritz and a quick paper towel, you may prevent 10% to maybe 15% nitro giving a foggy white appearance like blushed dope.

Epoxies are supposedly more resistant - only tried that way once, but It came out heavy! I know, practice and technique can overcome that. However...

Odd thought... not for most of us: diesel fuel and exhaust residue don't do well with dope finishes - they yellow light colors; don't wash out with cleaning solutions and even straight isopropyl doesn't bother them. Also, ether or kerosene in them seems to dissolve, or dissolve into, enamel finishes. Does kerosene act too much like turpentine (aka: "mineral spirits?")

Incidentally, Bob, 20 or likely more years back, the EPA was really cracking down on 'volatile organic solvents'. At one time, it got so you couldn't mix a newest batch of Aero-Gloss with the previous batch. SIG paints were a bit better off. SIG has survived, I think. Has Pactra resumed production of "CAB" (Cellulose Acetate Butyrate) dope? If you have either current, or a stash of earlier, compatible A-G, Fantastic!

...Some of this explains the extreme cost of today's model airplane dope and the newer possible substitutes for it?

There are automotive finishes compatible with butyrate dope. You may have a nearby auto paint store that can mix pigments into straight
Randolph butyrate Clear for any color ever used on cars, boats or (people-carrying) airplanes... Possibly in as small as a quart volume....

A little attention to technique! - they can build up weight in a hurry, but cover very well even used sparingly.

They were developed for auto repair/rebuild/custom shops, for reasonable labor hours billing. Generally, they flow out well, 'cure' (at least to sanding/buffing extent) quickly, and "sand" ( w/1000 or 1500 wet or dry, or rubbing compound ) within hours. Traditional butyrates did better with several days to a week curing... (but, thinned properly, usually came out lighter.)

Just some ramblings...
Old 11-04-2015, 06:00 AM
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Ramble on. I think pretty much any two part paint is fuelproof, whether polyester, epoxy or the acrylic automotive paints. There are rumors that a generic hardener in a good quality hardware store enamel is somewhat fuelproof. The good thing about the butyrate and water based paints is that a lot of the weight evaporates away, unfortunately they are VOCs.
Old 11-04-2015, 06:56 AM
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I just did some test painting. I used rustolium and then a coat of pollu U on top. seems to work great
Old 11-04-2015, 07:06 AM
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Originally Posted by Lou Crane View Post
Bob J and Clean
(Hi, Clean, it's been a while. Good to see you again!.)
(Bob, any further word on the K&B .28 scheduling?)

One thing I think I noticed missing so far ... how much nitro are we talking about? Nitro is an extreme solvent ...

Butyrates stand up pretty well to 5% nitro fuels, in my experience. 10% gets iffy, moreso if raw fuel sits on the model. With luck, a spritz and a quick paper towel, you may prevent 10% to maybe 15% nitro giving a foggy white appearance like blushed dope.

Epoxies are supposedly more resistant - only tried that way once, but It came out heavy! I know, practice and technique can overcome that. However...

Odd thought... not for most of us: diesel fuel and exhaust residue don't do well with dope finishes - they yellow light colors; don't wash out with cleaning solutions and even straight isopropyl doesn't bother them. Also, ether or kerosene in them seems to dissolve, or dissolve into, enamel finishes. Does kerosene act too much like turpentine (aka: "mineral spirits?")

Incidentally, Bob, 20 or likely more years back, the EPA was really cracking down on 'volatile organic solvents'. At one time, it got so you couldn't mix a newest batch of Aero-Gloss with the previous batch. SIG paints were a bit better off. SIG has survived, I think. Has Pactra resumed production of "CAB" (Cellulose Acetate Butyrate) dope? If you have either current, or a stash of earlier, compatible A-G, Fantastic!

...Some of this explains the extreme cost of today's model airplane dope and the newer possible substitutes for it?

There are automotive finishes compatible with butyrate dope. You may have a nearby auto paint store that can mix pigments into straight
Randolph butyrate Clear for any color ever used on cars, boats or (people-carrying) airplanes... Possibly in as small as a quart volume....

A little attention to technique! - they can build up weight in a hurry, but cover very well even used sparingly.

They were developed for auto repair/rebuild/custom shops, for reasonable labor hours billing. Generally, they flow out well, 'cure' (at least to sanding/buffing extent) quickly, and "sand" ( w/1000 or 1500 wet or dry, or rubbing compound ) within hours. Traditional butyrates did better with several days to a week curing... (but, thinned properly, usually came out lighter.)

Just some ramblings...
Note 1 I have the 28's in hand. (see the K&B .28 thread).
Note 2. Thanks for posting the dope info. The EPA is a Ying Yang thing. Pollution was getting STUPID in the 50's-70's (lake Erie caught on fire). But the good things had to change like dope composition. How many cars had paint problems when they went to water base paint in the 80's. And you can see fish in lake Erie again (but I wouldn't eat them). Ambroid changed there composition for the same reasons. Now if my distributors can get some (don't hold your breath) I will be a happy camper.
Mr. Bob
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