News:


  • April 27, 2024, 12:05:55 AM

Login with username, password and session length

« previous next »
Pages: [1]   Go Down

Author Topic: Randolph (Brodack) in between Certified (Sig)  (Read 1097 times)

Offline Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12808
Randolph (Brodack) in between Certified (Sig)
« on: June 18, 2023, 10:40:06 AM »
Just how incompatible are Randolph and Certified dopes?

I have a ton of Sig color, which I understand is relabeled Certified.  The last plane I finished I bought a quart of Certified clear for the undercoats, and that worked just fine.  I have a plane I'm starting to finish, which has a few coats of Certified clear on it -- but I'm not sure if I can get any more (please do not address the availability issue here -- comment on this separate thread instead).

What happens if I switch over to Randolph dope to finish the under-layers, then use Sig colors on top?  Will I have terrible adhesion problems, or will lower layers wrinkle -- or will it turn out fine?

If I can't put Randolph products in between layers of Certified, any suggestions on what to do?
Logged
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline kevin king

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1536
Re: Randolph (Brodack) in between Certified (Sig)
« Reply #1 on: June 18, 2023, 11:03:51 AM »
Its all butyrate. I would proceed if it were me. All the issues you mention can still happen even if its all one brand.
Logged

Offline Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12808
Re: Randolph (Brodack) in between Certified (Sig)
« Reply #2 on: June 18, 2023, 11:07:25 AM »
Quote from: kevin king on June 18, 2023, 11:03:51 AM
All the issues you mention can still happen even if its all one brand.

Uh -- thanks.  That makes me ever so confident.  I probably only have two or three years of finishing with dope spread over 45 years of modeling.  On the one hand, I haven't seen a hint of this sort of problem -- but on the other hand it's all been with Sig products.
Logged
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline doug coursey

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 214
Re: Randolph (Brodack) in between Certified (Sig)
« Reply #3 on: June 18, 2023, 08:11:16 PM »
Quote from: Tim Wescott on June 18, 2023, 10:40:06 AM
Just how incompatible are Randolph and Certified dopes?

I have a ton of Sig color, which I understand is relabeled Certified.  The last plane I finished I bought a quart of Certified clear for the undercoats, and that worked just fine.  I have a plane I'm starting to finish, which has a few coats of Certified clear on it -- but I'm not sure if I can get any more (please do not address the availability issue here -- comment on this separate thread instead).

What happens if I switch over to Randolph dope to finish the under-layers, then use Sig colors on top?  Will I have terrible adhesion problems, or will lower layers wrinkle -- or will it turn out fine?

If I can't put Randolph products in between layers of Certified, any suggestions on what to do?



  aircraft spruce website says not to mix certified and randolph products because its not always compatable         https://www.aircraftspruce.com/catalog/cspages/dopesthinnrsolvents3.php
Logged
AMA 21449

Offline Paul Smith

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 5801
Re: Randolph (Brodack) in between Certified (Sig)
« Reply #4 on: June 19, 2023, 07:14:25 AM »
According to my local airport supply store, the difference between Brodak, Randolph and Certified is the price alone.

His price for Certified is the least high of the three.  The words "lowest" and "cheaper" do not apply to any of these products.
Logged
Paul Smith

Offline Dave_Trible

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6153
Re: Randolph (Brodack) in between Certified (Sig)
« Reply #5 on: June 19, 2023, 01:25:25 PM »
I use largely Randolph clear under and over Sig colors with no issues.  For a  while I used Certified clear which was OK but two semi-issues;
1.  Certified has a LOT more solids in it.  It fills very well and fast but can end up a lot more heavy if not careful.  Randolph is thinner out of the can but I still cut it about 1/3 rd rather than 100% with the Certified.
2. Certified as a top coat over Sig color is fine except it doesn't really etch and adhere to the color.  Where damaged or chafed the clear will peal off like stretch wrap.  The solvent in the clear doesn't seem to have any effect on what is underneath.

Now with the apparent demise of Sig dope I am using Randolph throughout.  The only downside is that you'll have to buy your colors by the quart instead of smaller quantities.  I don't know much about Brodak dopes other than they give me a headache right away unlike the others so their solvent must be something different than the rest.

Dave
Logged
AMA 20934
FAA Certificate FA3ATY4T94

Offline doug coursey

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 214
Re: Randolph (Brodack) in between Certified (Sig)
« Reply #6 on: June 19, 2023, 07:01:42 PM »
Quote from: Paul Smith on June 19, 2023, 07:14:25 AM
According to my local airport supply store, the difference between Brodak, Randolph and Certified is the price alone.

His price for Certified is the least high of the three.  The words "lowest" and "cheaper" do not apply to any of these products.

$92 dollars for a quart of certified thinner :o
https://www.aircraftspruce.com/catalog/pnpages/09-11900.php
Logged
AMA 21449

Offline kevin king

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1536
Re: Randolph (Brodack) in between Certified (Sig)
« Reply #7 on: June 20, 2023, 06:57:56 PM »
Quote from: doug coursey on June 19, 2023, 07:01:42 PM
$92 dollars for a quart of certified thinner :o
https://www.aircraftspruce.com/catalog/pnpages/09-11900.php
92 dollars for a quart? that must be a mistake.
Logged

Offline doug coursey

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 214
Re: Randolph (Brodack) in between Certified (Sig)
« Reply #8 on: June 21, 2023, 04:46:05 AM »
Quote from: kevin king on June 20, 2023, 06:57:56 PM
92 dollars for a quart? that must be a mistake.

im sure it is..a gallon is only $72
im using randolph clear nitrate,sig super coat clear and brodak color and finnishing with brodak crystal clear on the same plane with no problem,im pretty sure its all made by randolph,i know the brodak is and pretty sure the sig is also randolph too...
Logged
AMA 21449

Offline doug coursey

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 214
Re: Randolph (Brodack) in between Certified (Sig)
« Reply #9 on: June 21, 2023, 04:54:34 AM »
Quote from: doug coursey on June 21, 2023, 04:46:05 AM
im sure it is..a gallon is only $72
im using randolph clear nitrate to attach the silk then sig supercoat clear to tighten the silk and then brodak color and finishing with brodak crystal clear on the same plane with no problem,im pretty sure its all made by randolph,i know the brodak is and pretty sure the sig is also randolph too...
Logged
AMA 21449

Advertise Here
Pages: [1]   Go Up
« previous next »
Tags:
 


Advertise Here