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Building Tips and technical articles. => Paint and finishing => Topic started by: kevin king on January 13, 2022, 01:08:43 AM
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Has anyone tried Rand-O-Fill and how does it compare to Sig Silver? I will be using it for blocker coats only. The product description seems like it would be what i need.
Kevin.
https://www.wagaero.com/restoration/covering-material-supplies/randolph-covering-materials/butyrate-dopes-thinner/rando-o-fill-silver-g-6303-quart.html
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Randolph is a good product and I haven't used Sig dope in many years. It is butyrate dope with aluminum powder in it. I mix my own for model work because I generally paint with nitrate dope. I don't think my way is cost effective for most though as the can of paste costs the same as a quart of dope. The coverage is good and being butyrate will be compatible where butyrate is. I wouldn't hesitate.
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I use Randolph Sil-Vo-Fill all the time. I've never used the SIG.
I just brush it on the plane after several coats of clear. I tried to spray it once with no success. Maybe too much solids. I want a lot of film build so spraying would be counter productive anyway.
Most of it gets sanded off. It helps to find the low spots.
The purpose of the product is to protect the dope from UV damage.
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Kevin,
If you look at some of the old school finishing videos from Windy you will see he used SIG Silver all the time. It is thinned 50/50 and sprays well for a thin light weight block coat. I use the Preval Spray system (~$6 home depot). One thing with silver, when you apply the first coat it will show all the nicks, dents and unfilled dope areas. What Windy would do is apply 1st coat, let it dry several days then sand down any problems recoat with clear then after dry hit it with the silver. Once you get a smooth surface, I would give one coat of clear then go to color.
Best, DennisT
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Picked up a quart of Randofill today. Will give it a try.
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I use Randolph Sil-Vo-Fill all the time. I've never used the SIG.
I just brush it on the plane after several coats of clear. I tried to spray it once with no success. Maybe too much solids. I want a lot of film build so spraying would be counter productive anyway.
Most of it gets sanded off. It helps to find the low spots.
The purpose of the product is to protect the dope from UV damage.
It's probably from not thinning enough or using a gun with too small of a tip. Touch up guns are 0.8 and 1.5 is better. Regardless just thin it until it does spray well. On the models I use a touch up gun.
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I don't know the exact thinning ratio. I doubt if anybody does, because, without extensive testing, you don't know the viscosity to begin with.
So I thin the dope in a mixing jar and give it a try. If it doesn't go, I add thinner and try again. By now, i can tell if it's ready by the feel of the stirring stick.
Maybe if I added enough thinner I could have sprayed it, but since it's base coat to sanded anyway, I just go to the brush.
The photos are from my first attempt at air brushing when I discovered that "modern" dope won't tolerate brushing over the base coat.
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It doesn't take extensive testing, just the right tool:
https://www.youtube.com/watch?v=_ngGy4Ra02Q
(Of course I also generally use the "looks about right, try it and see" method :) )
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It doesn't take extensive testing, just the right tool:
(Of course I also generally use the "looks about right, try it and see" method :) )
My extensive testing involves poring in to the cup, attaching the hose, squeezing the trigger and evaluating the quality of the cover. If needed add a bit more thinner. Often to the cup if it's a small batch or pore it back in the mixing container and add thinner. With enough experience you can tell how much is needed.
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Where a cup like that is handy would be in sharing information.
Lets you put a number on things, so that not everyone has to go though the trial and error process.
If I did more spraying, I would likely get one.
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Where a cup like that is handy would be in sharing information.
Lets you put a number on things, so that not everyone has to go though the trial and error process.
If I did more spraying, I would likely get one.
I saw the viscosity cup decades ago.
It would work good in a business where the modeler is not paying for the paint. In my size of operation the wasted paint and thinner would be unacceptable.
For example if you had a contract to paint an apartment or a factory. The test sample in the video uses as much paint as three of my models.
I do trial and error in clean glass cups. The "error" goes back into the can with zero loss.
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I saw the viscosity cup decades ago.
It would work good in a business where the modeler is not paying for the paint. In my size of operation the wasted paint and thinner would be unacceptable.
For example if you had a contract to paint an apartment or a factory. The test sample in the video uses as much paint as three of my models.
I do trial and error in clean glass cups. The "error" goes back into the can with zero loss.
There's isn't much waste though. Only the tiny amount that sticks to the cup which is near zero. The cups dips down in to your mixing jar and runs back in to your mixing jar. You then add reducer until you get the proper viscosity for spraying and then transfer what's in your jar to your spray gun. The advantage is significant when spraying expensive catalyzed finish onto expensive work. It virtually guarantees the correct viscosity and can be used between coats for each mix for application to insure consistency.
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Before all that stuff came into play, years ago, we all just dipped the stirring stick into the pot and lifted it about a foot up and took a good look at the droplet. The height it came up was the tell.
Could still work today.
Charles
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Before all that stuff came into play, years ago, we all just dipped the stirring stick into the pot and lifted it about a foot up and took a good look at the droplet. The height it came up was the tell.
Could still work today.
Charles
That's pretty much my method. The feel of the stirring stick is close enough. Even the smallest viscosity cup would take more than my whole project, not to mention that I'm using several colors, so that would be a lot of dipping and timing.
If it clogs the tip, add thinner. I have never yet made a mixture too thin to cover. If I ever did, I would dump it back into the mixing jar.
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I don't know the exact thinning ratio. I doubt if anybody does, because, without extensive testing, you don't know the viscosity to begin with.
So I thin the dope in a mixing jar and give it a try. If it doesn't go, I add thinner and try again. By now, i can tell if it's ready by the feel of the stirring stick.
Maybe if I added enough thinner I could have sprayed it, but since it's base coat to sanded anyway, I just go to the brush.
The photos are from my first attempt at air brushing when I discovered that "modern" dope won't tolerate brushing over the base coat.
Paul! I see why it was hard to spray. You definately need a bigger gun! Silver is to thick for an airbrush. I have the same airbrush and the amount of reduction depends on the paint you are spraying. A red paint has less pigment and more Dye, so you would use less thinner as compared to say a white that has alot of pigment, its thicker and harder to spray, so you reduce it more , ect.
Kevin