News:
2018----><---- T Shirt




  • October 19, 2018, 02:54:31 PM

Login with username, password and session length

Author Topic: ... Plasticizer...  (Read 1455 times)

Offline Bootlegger

  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2220
... Plasticizer...
« on: March 01, 2018, 04:41:15 PM »
  Just what does plasticizer do to dope? Does it help to reduce shrinkage in the finishing, wood and silk span not shrink as much?  Any help sure will be appreciated..
8th Air Force Veteran
Gil Causey
AMA# 6964


Offline George Truett

  • 2018 Supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 139
Re: ... Plasticizer...
« Reply #1 on: March 01, 2018, 05:27:07 PM »
In the late 60s a lot of the people I knew started finishing with Acrylic Lacquer from the auto body shop suppliers.  There were a huge selection of colors and it was relatively affordable but over open structures and sometimes sheeted areas it would craze or spider web after a few flights.  Southern R/C sold plasticizer, you added something like a tablespoon to a quart of paint and it would not do it or at least not as badly.  I think it just makes the paint less brittle after it dries.  As I recall some people used something else for the same thing, maybe Oil of Wintergreen?  George T

Online Juan Valentin

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 444
  • USAF 1969-73 ANG 73-77
Re: ... Plasticizer...
« Reply #2 on: March 03, 2018, 05:08:44 AM »
Hello Bootlegger
                        I was reading an old American modeler from may/june 1966 and there is an article about a scale Piper Comanche and the author used acrylic lacquer. The plasticizer he used was Almond oil. He wrote not to use Almond Extract which is a flavoring material. He used the acrylic lacquer over dope.
                                                                                                                                                                                             Juan

Offline Massimo Rimoldi

  • Trade Count: (0)
  • Lieutenant
  • ***
  • Posts: 78
Re: ... Plasticizer...
« Reply #3 on: March 03, 2018, 10:00:58 AM »
  Just what does plasticizer do to dope? Does it help to reduce shrinkage in the finishing, wood and silk span not shrink as much?  Any help sure will be appreciated..

Hi.
The purpose of the plasticizer is to make the dope more flexible..
Its use is evident long after the application of the dope because solvents require weeks (sometimes months) to evaporate completely.
Camphor and castor oil are excellent plasticizers for dope.
Usually the products that we find on the market already contain plasticizers, usually solvents which by their nature tend to remain trapped in the product, but if we consider it opportune it is often possible to add 2-5% of castor oil.
The addition of high percentages of oil produce a material that vaguely resembles the rubber.

Regards, Massimo

Offline Dan McEntee

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2901
Re: ... Plasticizer...
« Reply #4 on: March 03, 2018, 12:49:19 PM »
   Back in the good old days, (whenever that happens to be for you!) it was common to see in instructions and building articles to add three to five drops of castor oil to thinned dope for the final colors and clear, to act as a plasticizer.  The Southern R/C product  that was mentioned was probably Dave Brown Flex-All. The Sountern R/C products, Dave brown Products ab some others are all under the umbrella of Ohio Superstar Products or something like that. I may have that mixed up. I have tried to get the hobby shop to find me some flex-All but apparently they only deal direct now. The last time I used it, it looked just like medicinal castor oil, fairly clear. A drop of each on  the tip of my tongue tasted the same. Mot very scientific, I know, but it was some way to test it. Bill Byles sent me the name  of a chemical to use for a plasticizer, but I couldn't pronounce it so I know i can't remember what it is! I'll see if I can dig that up and post it on this thread.
  Type at you later,
  Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline Dan McEntee

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2901
Re: ... Plasticizer...
« Reply #5 on: March 03, 2018, 02:39:13 PM »
  The chemical I was referring to in my last post is tricrescyl phosphate. Bill said that would work "if you can get it." I don't know what it is much less know where to get it! I'll have to ask the guys at the automotive paint store.
  Type at you later,
  Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline Avaiojet

  • 2018 Supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6525
Re: ... Plasticizer...
« Reply #6 on: March 05, 2018, 04:35:38 PM »
Those of us who painted custom cars, called this product Flex Agent.

A quick Google might bring up more information. Maybe.

Trump Derangement Syndrome. TDS

Avaiojet Derangement Syndrome. ADS

Please visit my updated Website! www.cfcgraphics.com

If you're Trolled, you know you're doing something right.

Alpha Mike Foxtrot.

Owner of CFC Graphics. "Model Airplane Graphics from a Model Airplane Builder."

"No one has ever made a difference by being like everyone else."

Marcus Cordeiro, The "Mark of Excellence," you will not be forgotten.

I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.

"Ya gotta love it when a plane comes together."

Proverb 11.9  "With his mouth the Godless destroys his neighbor..."

"Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Offline Dan McEntee

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2901
Re: ... Plasticizer...
« Reply #7 on: March 05, 2018, 05:41:31 PM »
Hi Dan.  The TCP mentioned was used by Shell Oil in the late 50's as a fuel additive.  They advertised it and we smart ass teen age jump jockey's told the customers it meant Tom Cat @#$%.  LL~ LL~ LL~ LL~

    I finally googled it and found that it is some really bad stuff we don't want to mess with. I can remember commercials for some gas company touting TCP. I think medicinal castor oil will work as good as anything else. I'll have to try it if I can't get Flew-All anymore.
  Type at you later,
   Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline George Truett

  • 2018 Supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 139
Re: ... Plasticizer...
« Reply #8 on: March 05, 2018, 05:46:43 PM »
Still available, just costs more.  http://www.ohio-superstar.com/dave-brown-product-line/

Offline Dan McEntee

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2901
Re: ... Plasticizer...
« Reply #9 on: March 05, 2018, 09:32:56 PM »
Still available, just costs more.  http://www.ohio-superstar.com/dave-brown-product-line/
.
.

    Yeah, but none of the main line distributors will carry it. Kind of hard for a hobby shop to get it if no distributor carries it. It gets real expensive when you tack on shipping. I don't mind paying retail at the hobby shop, and then some one else makes a buck rt two, and I save shipping. And I have the fun of looking around and browsing the hobby shop. Call me an old school old fart but that's the way I see it.
   Type at you later,
  Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline Massimo Rimoldi

  • Trade Count: (0)
  • Lieutenant
  • ***
  • Posts: 78
Re: ... Plasticizer...
« Reply #10 on: March 06, 2018, 12:33:46 AM »
    I think medicinal castor oil will work as good as anything else.

The medicinal grade is not necessary.
The castor oil we use for the fuel is OK.

Massimo

Offline Massimo Rimoldi

  • Trade Count: (0)
  • Lieutenant
  • ***
  • Posts: 78
Re: ... Plasticizer...
« Reply #11 on: March 06, 2018, 09:00:34 AM »
Yes, all products based on nitrocellulose contain a plasticizer.
Otherwise the product would crack very quickly because nitrocellulose is very fragile.
Usually, however, currently very low evaporation solvents are used and these tend to leave the film.
In fact we notice that over time the coverage of our wings becomes brittle and after years (if the model survives) is covered with cracks.
Adding a small percentage of castor oil to the dope increases the overall flexibility and above all castor oil does not evaporate ....

Massimo
« Last Edit: March 06, 2018, 10:50:47 AM by Massimo Rimoldi »

Offline kevin king

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 173
Re: ... Plasticizer...
« Reply #12 on: May 21, 2018, 03:27:12 PM »
   Back in the good old days, (whenever that happens to be for you!) it was common to see in instructions and building articles to add three to five drops of castor oil to thinned dope for the final colors and clear, to act as a plasticizer.  The Southern R/C product  that was mentioned was probably Dave Brown Flex-All. The Sountern R/C products, Dave brown Products ab some others are all under the umbrella of Ohio Superstar Products or something like that. I may have that mixed up. I have tried to get the hobby shop to find me some flex-All but apparently they only deal direct now. The last time I used it, it looked just like medicinal castor oil, fairly clear. A drop of each on  the tip of my tongue tasted the same. Mot very scientific, I know, but it was some way to test it. Bill Byles sent me the name  of a chemical to use for a plasticizer, but I couldn't pronounce it so I know i can't remember what it is! I'll see if I can dig that up and post it on this thread.
  Type at you later,
  Dan McEntee
So Dan, did you buy the Dave Brown Flex All, almond oil, medicinal castor oil, or castor oil used in our fuel?

Offline Dan McEntee

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2901
Re: ... Plasticizer...
« Reply #13 on: May 21, 2018, 05:40:37 PM »
  Hi Kevin;
  I used to buy Flexall when they could get it at the hobby shop. I don't think the main line distributors carry it or Ohio Superstar doesn't deal with them any more. Kind of like Sonic Tronics products have to be bought directly from them now and several others.  Massimo seems to think that castor for our fuel will work fine. I think the medicinal stuff may be a safer bet as it is processed more and all the waxes, gums and such should be removed. That is what Flex-All looked and tasted like to me. I haven't tried it in a while and I have some free flight models that need doping and I'm going to try it on the tissue on those.
  Type at you later,
  Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline kevin king

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 173
Re: ... Plasticizer...
« Reply #14 on: May 21, 2018, 06:36:33 PM »
  Hi Kevin;
  I used to buy Flexall when they could get it at the hobby shop. I don't think the main line distributors carry it or Ohio Superstar doesn't deal with them any more. Kind of like Sonic Tronics products have to be bought directly from them now and several others.  Massimo seems to think that castor for our fuel will work fine. I think the medicinal stuff may be a safer bet as it is processed more and all the waxes, gums and such should be removed. That is what Flex-All looked and tasted like to me. I haven't tried it in a while and I have some free flight models that need doping and I'm going to try it on the tissue on those.
  Type at you later,
  Dan McEntee
Yes, I did talk to Massimo, because he said all products based on 'Nitrocellulose' lacquer, which to me, means Nitrate dope, not Butyrate. Yes if you test it out let us all know. Thanks!

Offline billbyles

  • AMA Member
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 619
Re: ... Plasticizer...
« Reply #15 on: May 23, 2018, 02:16:35 PM »
  Hi Kevin;
  I used to buy Flexall when they could get it at the hobby shop. I don't think the main line distributors carry it or Ohio Superstar doesn't deal with them any more. Kind of like Sonic Tronics products have to be bought directly from them now and several others.  Massimo seems to think that castor for our fuel will work fine. I think the medicinal stuff may be a safer bet as it is processed more and all the waxes, gums and such should be removed. That is what Flex-All looked and tasted like to me. I haven't tried it in a while and I have some free flight models that need doping and I'm going to try it on the tissue on those.
  Type at you later,
  Dan McEntee

Hi Dan,

The tricrescyl phosphate was the plasticizer used in dope at least up until the seventies and I used lots of it on full-scale airplanes.  For my models I have always used Dave Brown's "Flex All".  "Flex All" is not a hazmat material so the shipping should not be out of the ordinary.  The only super hazardous material that I have encountered in dope is when covering old-time airplanes with either grade-A cotton or linen.  The first coat down on those materials had to be nitrate dope mixed with an anti-fungal chemical to prevent mildew from starting in the organic covering material.  The anti-fungal chemical turned the dope kind of a pink color, and warnings were printed on the dope can about the health hazards of the anti-fungal material.

Anti-fungal dope is not much of a requirement these days since I don't know where you can even buy grade-A cotton or linen (possibly from a source in England but I'm not sure.)  Aircraft Spruce used to sell it but no longer. 
Bill Byles
AMA 20913
So. Cal.

Offline kevin king

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 173
Re: ... Plasticizer...
« Reply #16 on: May 30, 2018, 08:58:45 PM »
Tomorrow I will get the 2 bottles of Flex All I ordered from Ohio Superstar Products. They are 8.95 each. I have a feeling this stuff is going to be discontinued soon. http://www.ohio-superstar.com/dave-brown-product-line/flexall-paint-plasticizer

Offline Steve Helmick

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 8313
Re: ... Plasticizer...
« Reply #17 on: June 12, 2018, 06:07:52 PM »
Having used castor oil for plasticizer in clear dope on free flight models, the one thing you want to keep in mind is that it reduces the adhesive qualities of the clear for applying covering and possibly other uses. I'd expect more problems with masking tape pulling up the base color, for instance. No Bueno. Do test panels.  D>K Steve
In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.

In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

"Be polite, be professional, but have a plan to kill everybody you meet." General Mattis.

Offline Massimo Rimoldi

  • Trade Count: (0)
  • Lieutenant
  • ***
  • Posts: 78
Re: ... Plasticizer...
« Reply #18 on: June 13, 2018, 01:14:56 AM »
Hi.

If the amount of castor oil is not exaggerated (2-5%), adhesion problems are unlikely to occur.
It is much easier to have this problem by adding exaggerated quantities of talc or zinc stearate as fillers.
When we apply a coat of paint on the previous one (especially if the first one is nitrocellulose), the main mechanism that guarantees adhesion between the layers is of a chemical nature.
Translated into simple words: the solvents of the second coat attack and partially dissolve the substrate, in this way the second penetrates into the first.
Also for this reason the paint must adequately "wet" the substrate and do not dry too quickly.

However, I absolutely agree that a preventive test is to be recommended.

Massimo


Tags: