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Author Topic: Finishing over Sig Butrate  (Read 538 times)

Offline Steve Dwyer

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Finishing over Sig Butrate
« on: February 13, 2018, 06:04:43 PM »
I'm ready to apply colors to my plans built  ME109, would like to use the Randolph line because of what appears a greater variety of color selections than Sig or Brodak. Should I have any concerns with compatibility the silk is adhered and sealed using Sig Butrate.  What about shrinkage issues if I stay with their Butrate or go with Nitrate?
There's tons of info on this topic can someone give me a straight answer and recommendation of what to use.
Steve


Offline Dan McEntee

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Re: Finishing over Sig Butrate
« Reply #1 on: February 13, 2018, 07:41:40 PM »
   To start with, you can NOT put nitrate over anything. It has to be applied first. I believe that Randolphs is compatible with SIG. If you have used straight tautening butyrate this point, you will want to make sure you use non-tautening colors to finish and clear coat. Allowing plenty of time between steps to let things gas off is also helpful.
  Search out ANYTHING written by Bill Byles on here. He does this professionally and does models also. You can take his word to the bank.
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Offline Steve Dwyer

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Re: Finishing over Sig Butrate
« Reply #2 on: February 13, 2018, 08:53:17 PM »
Dan, Ok I understand about the nitrate, but why is it I must use non tautening butyrate after using tautening butyrate? Does it over tighten more than the structure can handle?  Actually I've use Sig Butyrate clear Super Coat to install the silk followed with several more clear coats. Is it now acceptable to use the Randolph NTB colors and clear to follow?
Steve

Offline Dan McEntee

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Re: Finishing over Sig Butrate
« Reply #3 on: February 13, 2018, 09:48:26 PM »
   If you continue with tautening dope, you just stand a chance of inducing warps as the dope continues to shrink, and as the model ages, having the covering split easily. It just keeps shrinking over time. Doing the build ups, and covering applications and initial clear build up with tautening dope is what gets you the tight appearance, so you are on track there. Randalphs may just need to be thinned a bit more to spray when you shoot it, or even if brushing and will need to be plasticized to negate the shrinking properties. Dave Brown Flex-All is available for that purpose and works well. If you decide to proceed with SIG colors, they are all based on SIG Lite Coat, which is non-tautening dope. Both Butyrate and Nitrate come in tautening and non-tautening varieties. It would still be well worth your time to search out posts by Bill Byles on the subject as he gives a great dissertation on how to finish with dope on several occasions. Bill ought to just write something up and have Sparky pin it to the top of this section.
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Offline Dennis Toth

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Re: Finishing over Sig Butrate
« Reply #4 on: February 14, 2018, 06:35:32 AM »
Steve,
You didn't indicate if this was electric or IC. Looking at the picture is looks like it could be electric. If so, you could use any enamal type paint for camo colors doesn't have to be dope. Sig is compatable over the Randolph, Brodak is actually Randolph that Windy worked with Randolph to get the right amount of plasticizer for our type of finish. I personally like dope as it is still the lightest. For IC I will top coat with 2K Diamond clear (lots of info on here about that product). If you use Brodak final clear coats you can rub it out after 3 days, Sig needs several weeks to gas off to get hard enough to buff out fully.

Best,   DennisT


Online Avaiojet

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Re: Finishing over Sig Butrate
« Reply #5 on: February 14, 2018, 07:22:35 AM »
Steve,

What about spray equipment?

Do you have what you need to apply paint with spray equipment, spray gun,  airbrush?

CB

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Offline Steve Dwyer

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Re: Finishing over Sig Butrate
« Reply #6 on: February 14, 2018, 06:17:18 PM »
It really appears I should stay away from the Randolph products and stick with Sig or Brodak, even the non tautening Randolph may give me trouble with the silk. It's unfortunate either line offers the variety of colors and the price favorability Randolph does. It's obvious the development of these paints is reflected in the price above the Randolph price points. I'll check out the Bill Byles info using dope. The front mounts are for a gas engine and I plan to spray the finishes. I have a spray system.

Thanks gents for getting me straight I'll send along some photos as I proceed.

Steve

Offline Dan McEntee

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Re: Finishing over Sig Butrate
« Reply #7 on: February 14, 2018, 06:55:25 PM »
  Hi Steve;
    Are you looking for camo colors? For some reason, olive drab  was dropped by SIG, but you wouldn't paint an ME-109 that color. If there is a good auto, olive paint store near you, look into what colors of pigment they can offer, and add that to your clear. or google search mixing ratios and colors required and mix your own using SIG or Brodak. Lots of ways to get the color you want and still stick with dope.
  Good luck and have fun,
   Dan McEntee
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Offline Alan Resinger

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Re: Finishing over Sig Butrate
« Reply #8 on: February 15, 2018, 08:54:15 PM »
SIG has only one dope that is taughtening dope. That is clear Supercoat.  All SIG colors are non taughtening  formulae.  SIG Lite Coat clear is non taughtening.  Using Randolph colors is no problem over SIG.  Randolph colors are also non taughtening.  Randolph  has several different clear varieties. A-1690 is clear non taughtening.  Most of the other clears are tinted to make it easier to judge coverage for substrates on full sized fabric covered aircraft.  Stay away from nitrate dope.  It is a holdover from years long gone  by and we modelers gain little or nothing from using it.  Use Randolf colors and if clearcoating after you have your color on use A-1690 clear.

Offline Steve Dwyer

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Re: Finishing over Sig Butrate
« Reply #9 on: February 16, 2018, 06:26:53 AM »
I think I'm getting close here. Based on everyone's inputs to date I have the following questions, hopefully this will wrap it up.

1. Can the Randolph A-1690 clear butyrate non tautening clear be used in place of the Sig colored Lite Coat? I assume Randolph uses the A-1690 to add it's colors.

2. I've read where others have used DuPont colors from an auto finishers to add color to the A-1690 is this acceptable and compatible?

3. Can the Randolph 9701 butyrate clear tautening be used in place of Sigs Supercoat we use to install and tighten the silk covering and seal the open bays?

3. What is the function of the Randolph tinted butyrate with added plasticizers? I thought the plasticizers can cause problems later. also I read where Sig and Brodak with Windy played with the plasticizers to arrive at a formulation better suited for our model purpose.

Please advise if you have experience using these Randolph products instead of Sigs with good results. I understand I can apply Randolph over the Sig and I'm not using a camo color here, I plan to follow the Africa colors tan on top with sky blue on the underside, possibly some olive splashes in the tan field, I guess this is a bit camo at that.

Steve

Offline Steve Dwyer

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Re: Finishing over Sig Butrate
« Reply #10 on: February 19, 2018, 04:54:30 PM »
I finally had a chance to search out the information written by Bill Byles some years back.  His info answered my questions.

Thanks much for the help,
Steve


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