News:



  • March 29, 2024, 07:22:30 AM

Login with username, password and session length

Author Topic: Weather and dope  (Read 943 times)

Offline Matt Brown

  • 23 supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 287
Weather and dope
« on: March 30, 2022, 07:24:58 AM »
I’ve always heard that weather, specifically the humidity affects the finish with dope. Does this only matter on the colors and final clear coat? Is it okay to brush on the first few coats before I apply carbon veil or silkspan and successive coats up to the color stage?

Thanks, Matt

Offline Dan McEntee

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6823
Re: Weather and dope
« Reply #1 on: March 30, 2022, 07:50:17 AM »
I’ve always heard that weather, specifically the humidity affects the finish with dope. Does this only matter on the colors and final clear coat? Is it okay to brush on the first few coats before I apply carbon veil or silkspan and successive coats up to the color stage?

Thanks, Matt

   Yes, you can do your build ups and such, just don't do it outside in the rain!! When you get to the finish coats is when you need to watch the humidity and add some retarder to the dope if necessary.
    Type at you later,
   Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline Matt Brown

  • 23 supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 287
Re: Weather and dope
« Reply #2 on: March 30, 2022, 08:15:18 AM »
Thanks Dan. That’s what I thought but wanted to make sure. I’m working towards putting base coats on the bare wood today out in my garage but rain is in the forecast.

Matt

Offline Paul Smith

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 5793
Re: Weather and dope
« Reply #3 on: March 30, 2022, 08:26:04 AM »
Randolph says (in effect) dope will blush if the humidity is over 50%.  So do your doping in the dry season of inside a humidity-controlled booth.

Another fix is a gallon of retarder, which is a slow-drying solvent.  Subsitute a small percentage of your thinner with retarder and you can tolerate a lot more humidity.

Retarder is a important tool in every paint shop.  As a bonus, the clear coat is shinier with a bit of retarder.
Paul Smith

Offline wwwarbird

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 7961
  • Welcome to the Stunt Hanger.
Re: Weather and dope
« Reply #4 on: March 30, 2022, 06:48:19 PM »

 You really only need to be concerned during your final finish and spraying work. If it's too humid there is a potential for "blushing" which leaves you with a foggy look to the finish of which the level of fogginess can vary. Experience and careful use of retarder in these conditions can help. During the build and until you get to those last final finish stages don't worry and just proceed with all of your other dope work as normal.
Narrowly averting disaster since 1964! 

Wayne Willey
Albert Lea, MN U.S.A. IC C/L Aircraft Modeler, Ex AMA member

Offline Jim Svitko

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 691
Re: Weather and dope
« Reply #5 on: March 30, 2022, 09:44:42 PM »
I also pay attention to the dew point when applying colors and final clear.  The evaporation of solvents will lower the surface temperature.  If the dew point is high enough, moisture will condense and cause blushing if the surface can cool to the dew point.

Offline kevin king

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1525
Re: Weather and dope
« Reply #6 on: April 01, 2022, 02:14:08 AM »
Speaking of trapping moisture, Ive always found it odd to dope over silkspan thats been dampened with water. Just sayin.

Offline Dan McEntee

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6823
Re: Weather and dope
« Reply #7 on: April 01, 2022, 01:51:48 PM »
  Well, I have spent the last couple of months digitizing Windy videos, and as a result of that, watching a pretty good part of each one, and you would be amazed at how many times I saw him shoot paint outside with snow on the ground! Just some small parts and such, sometimes a color coat and sometimes clear, but when he is to a point in something where it needs paint, he will mention what the conditions are at the time. Kevin puts up about 3 or 4 new videos everyday so it's worth checking in now and then on the Walt Brownell Channel. I am just finishing the "Using Brodak Dope" series of 5 tapes plus some on ink lines and buffing out paint and they should go up some time next week. I'm a little ahead of Kevin, and we are trying to do these in some kind of order where possible. I also just did the 6 tape series on building the Brodak Original Nobler and it will be up soon. All of these construction series videos have some kind of paint and prep information on them, and an advantage to watching them on line is that you can skip through stuff you don't need to see at that point faster and go over it again and again. And a lot of this information applies to using other types of systems also.
  Type at you later,
   Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline john e. holliday

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 22752
Re: Weather and dope
« Reply #8 on: April 01, 2022, 02:20:55 PM »
I was wanting to get my version of the Thirteen ready for VSC.  The clear coat i had applied the day before turned cloudy.  But I wanted to apply another coat of clear.  Sat out side the basement and applied the clear and the temps were in the low 40F degrees.  Hung it on the hook inside the basement door.   Next morning I went to check it out.  The finish was clear and shiny.  But I don't do dope anymore. D>K
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
AMA 23530  Have fun as I have and I am still breaking a record.


Advertise Here
Tags:
 


Advertise Here