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Building Tips and technical articles. => Paint and finishing => Topic started by: Motorman on December 25, 2019, 03:34:53 PM
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I've had good success w/ Zn Stearate for decades. I bought it from a chemical supply house and believe it is relatively pure. I like it because there is no risk of "other stuff" that might be added to Talc meant for human skins uses.
I mix 2 tablespoons MAX per pint of unthinned dope. I use a lot of thinner and often use less than the 2 tablespoons Zn St. I brush on after the 1st four coats of clear dope over tissue, Polyspan, or carbon matt. It powders up nicely when sanded
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Randy Smith has had it 8n his line of products for as long as I can remember, and it has been discussed in great detail how to use it on the forums.
HAPPY HOLIDAYS!!!!
Dan McEntee
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I've had some adhesion issues with zinc stearate. I used pharmaceutical quality. I'm not a baby power fan either. I have some industrial talc I tried and it worked OK. At this point, I just use butyrate clear and build it up without fillers.
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Adhesion problems often are due to too much filler material mixed into the dope. Hence my recommendation on the qty of Zn. St. per pint of dope
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I find that just clear generally sticks to just clear. ;D
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MM,
Main reason for using Zn instead of Talc is weight. Zn is 18 lbs/ft3, Talc is 168 lbs/ft3. Talc also absorbs lots of dope making it even heavier. I like Jim's recipe for making the filler coat. The trick is to let it dry so when you sand it powders off. I like to let each coat dry overnight before sanding. But if you need to go quick the Brodak thinner in either Brodak or Sig dope pretty much dry's in a 4 - 6 ish hours.
Best, DennisT
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Has anyone sprayed the Zn St and butyrate?
Seems with say 60% ish thinner it should be sprayable in say a cheap Pravel spray bottle. Should be lighter then the primers with the acrylic lacquer as the carrer and white pigment. I know it's not what you put on but what you sand off, but you still need the solid block color base.
Best, DennisT
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I find that just clear generally sticks to just clear. ;D
I am with you, the best way to fill is to add more of the same and sand it off till there ain't no more holes. Learned that from Gieseke. But mine still suck compared to his so I might be wrong. LL~
If you add 2oz of clear and sand off 1.99oz why add something to it that may end up on your masking tape later?
Since returning, I have tried the Filler/Primer route and this is the last one. I am back to paint only, lots of sandpaper and reviving the lost art of wet sanding.
Ken
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I am with you, the best way to fill is to add more of the same and sand it off till there ain't no more holes. Learned that from Gieseke. But mine still suck compared to his so I might be wrong. LL~
If you add 2oz of clear and sand off 1.99oz why add something to it that may end up on your masking tape later?
Since returning, I have tried the Filler/Primer route and this is the last one. I am back to paint only, lots of sandpaper and reviving the lost art of wet sanding.
Ken
I've painted 5 models and applied primer on all of them. NOTHING, no paint/clear, came off on the tape! If paint comes off with tape you're doing something wrong.
Choose wisely the products you elect to use.
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If paint comes off with tape you're doing something wrong.
You got it, what I was doing wrong was using filler and primer when I didn't know how. I used to use nothing but AeroGloss colored dope from the 4th coat on. I would brush about 5 coats sanded then wet-sanded after the third color between coats. Rubbed and polished it was as fine a finish as you could get in the day. Can't get AeroGloss anymore and the Sig & Brodak dopes just don't sand as well. Rustoleum does, especially wet sanding so I am going back to the old way of using sanded solid until there aren't any more dings to fill (I also use colored dope to fill the little blemishes - let a small amount of color set out and thicken and use it to fills those places where the grain won the battle on the early coats). This method is about the lightest you can find. Maybe takes a bit longer but what else did you have to do while watching TV. Rubbing and polishing used to be the fun part.
I have tried it everybody else way on my last two planes after returning and turned two really well sanded, smooth and light air-frames into two overweight planes with finishes that will be looking over the tops of other ships to even see the front row. Luckily they fly great.
I readily admit that except perhaps for weight, the new stuff and methods are better but I have limited building space and no where to set up a spray station or the money to buy equipment that may be used once a year. So, I am going back to the old ways.
Do you have a phone number I can text some images to? I may want you to do some graphics for me if they are not too expensive. Waterslide didn't work, too big I guess and I really like vinyl better anyway. If not I can stick them on here.
Ken
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Ken,
We need to talk. LL~ LL~ LL~ LL~ LL~
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Well, as always, do what you want.