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Author Topic: Knotts Gelatin  (Read 2145 times)

Offline Guy Fuller

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Knotts Gelatin
« on: February 25, 2009, 10:42:20 PM »
OK, one of my co-fliers this weekend mentioned the use of Knotts Gelatin as a filler over the substrate ( balsa wood, foam, etc. ) anyone here ever use it?  If so are you just laying the sheets down and then brushing over with water?  Thanks.

Guy
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Alan Hahn

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Re: Knotts Gelatin
« Reply #1 on: February 26, 2009, 11:24:17 AM »
I have never used it, but I once read about it used to help fill the weave on a silk finish. I'm guessing you just follow the recipe on the box, then apply it over the silk with a brush (lukewarm??). That's what I recall, so clearly you want to do a test sample first.
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Offline Larry Fulwider

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Re: Knotts Gelatin
« Reply #2 on: February 26, 2009, 11:39:21 AM »
Quote from: Guy Fuller on February 25, 2009, 10:42:20 PM
OK, one of my co-fliers this weekend mentioned the use of Knotts Gelatin as a filler over the substrate ( balsa wood, foam, etc. ) anyone here ever use it?  If so are you just laying the sheets down and then brushing over with water?  Thanks.

Guy

It works OK if you keep the plane refrigerated.  ;D

BTW, it is KNOX gelatin -- there was some sort of spoof many years ago about Knox, and part of the spoof was the name "Knots" -- which has lasted longer than the joke.

Larry Fulwider
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Offline Guy Fuller

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Re: Knotts Gelatin
« Reply #3 on: February 26, 2009, 08:36:48 PM »
Thanks Larry,  I may try it on the next quickie design just to get a feel for it.  I'll revive this thread, then,  and let you know how I make out.

Guy
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Offline Steve Helmick

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Re: Knox Gelatin
« Reply #4 on: February 26, 2009, 10:54:22 PM »
I used it to stick on silk, when we lived out in the desert. Dope the framework as usual. Wet the silk as usual. Brush on the gelatin, being sure to have it well dissolved and smooth. DO NOT get any on the open bays, or it will cause a boo-boo. When it's well dried, paint with several coats of clear dope as usual, and trim the excess silk. When that is dry, it's said that you can use the gelatin mix to fill the weave, but I didn't try that. The areas that had the gelatin were very nicely sealed, tho.  D>K Steve
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Offline dennis lipsett

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Re: Knotts Gelatin
« Reply #5 on: February 28, 2009, 08:56:05 PM »
Knox gelatin is an old trick and was used in the early days of the giant scale movement in the 80's There was always one warning to using it. NEVER! put on a 2nd coat. It will get lumpy and you cannot sand it out. Some also used Niagra starch as a filler. the same warning applies to this product too.
dennis
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Offline Guy Fuller

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Re: Knotts Gelatin
« Reply #6 on: March 08, 2009, 07:19:30 PM »
Hey Ty what is zinc stearate?  Haven't heard of that one yet.

Guy
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Offline Guy Fuller

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Re: Knotts Gelatin
« Reply #7 on: March 08, 2009, 07:21:44 PM »
Humm!  You gotta love the internet.

Zinc stearate (Zn(C18H35O2)2) is a zinc soap that repels water. It is insoluble in polar solvents such as alcohol and ether but soluble in aromatic hydrocarbons, e.g. benzene and chlorinated hydrocarbons when heated. It is the most powerful mold release agent among all metal soaps. It contains no electrolyte and has a hydrophobic effect. Its main application areas are the plastics and rubber industry where it is used as a releasing agent and lubricant which can be easily incorporated.

Guy
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Offline Clint Ormosen

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Re: Knotts Gelatin
« Reply #8 on: March 10, 2009, 01:50:39 AM »
I'm still trying to figure out exactly why guys are always trying to put stuff in the paint to a act as a "filler". Is it just you can use one less coat of dope? I don't seem to have any trouble filling the wood and silkspan with 3-4 coats of plain ol' nitrate dope. Why put stuff in that could be a potential problem later. None of this stuff is going to adhere to the surface as well as straight dope. I've seen problems with talc, corn starch, gelatin, balsa dust, you name it. Why risk it? ???
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Offline sleepy gomez

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Re: Knotts Gelatin
« Reply #9 on: April 13, 2009, 08:21:16 AM »
I have used Knox unflavored gelatin for 37 years to seal foam (after tissue or silkspan) so that it can be painted with any paint or thinner.  I developed and published this method in American Aircraft Modeler, Feb. 1973.   I mix one packet of Knox unflavored gelatin with two ounces of HOT water.  Brush this on and allow to dry.  Work it before it cools. You can now pour lacquer thinner on the foam!  Do any sanding before the gelatin is applied.  SLEEPY
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