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Building Tips and technical articles. => Paint and finishing => Topic started by: Roger Vizioli on April 26, 2014, 10:02:44 PM
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Has anyone used RAND O FILL (Silver) non taughtening dope?
Might be a good "pore filler" for Polyspan.
Comments re: good, bad, light. heavy etc appreciated.
Thanks, H^^
Roger V.
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Not specifically about Rand-O-fill,, but more silvers in general,,
in my experience,, silver is a generally bad idea,, it has low integrity and at times very very poor adhesion for overcoats,, I think you are much better off using dope and talc, ,or some of the other more common fillers in dope,,
for the record, it is my experience that silver is used on full sized airframes to protect the fabric from ultraviolet degradation since dope has no UV protective qualities,,
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I agree 110% with Mark points, and then some.
In my opinion and experience, and in general in our C/L dope finishing world, at any stage in your finishing process, silver anything sucks and ends up becoming a pain in the a--, period. y1
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Thank you Wayne and Mark! good info.
I wont throw away my talc! :-)
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In reality, my planes are subject to more Hangar Rash than UV exposure.
Roger V.
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Roger- Good responses for the Rando-Fil. Yes for full size fabric covered airplanes, no for models. I spent a 30 year career launching satellites out of the Cape. Here's a nice video that will show you another part of the Florida coast from the air. Be sure you have the sound on. http://vimeo.com/69353642
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There is no sound on this computer. But, I guess the brain plays games as it felt like I was right in the pilots seat. Thanks for a great video.
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I tried it once. I won't again.
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Roger- Good responses for the Rando-Fil. Yes for full size fabric covered airplanes, no for models. I spent a 30 year career launching satellites out of the Cape. Here's a nice video that will show you another part of the Florida coast from the air. Be sure you have the sound on. http://vimeo.com/69353642
Don,
Great Video, thanks!
We might have crossed paths "down here" years ago. First launch was Atlas/ Echo A-12 in Jan 1964.
Moved here in 1966 for the Apollo Program and have maintained a home here as we "traveled to many places" on company business. Still here and loving it!
Roger
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I use the Sil-Vo-Fil as a preliminary undercoat before the actual color. It is intended as a UV blocker to protect the underlaying dope from solar damage. Most of mine gets sanded off, leaving telltale silver in the low spots.
As an aside, it tried mixing sil-vo-fil with another color and it didn't work at all.
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Roger,
Silver dope has been used by several top fliers as the first color coat to detect flaws. The idea is to get the substrate smooth and then spray on the silver. At this point you will likely have a good cry. The ship will have rough spots, dry spots, dings you thought you took care of. One tip is to use Brodak Silver. They worked on this to get a formula that dries hard in a day or so (SIG silver works but takes two weeks to dry per coat). Once dry start block sanding it off (hand sand on the open bay section and go slow so as not to sand through at the ribs). Once you get most of it off you will see the problem areas that you need to fix. Once those are addressed give the whole ship a final sanding with 420, wipe down with degreaser and give it a second coat. This time will not hurt as much, touch up whatever shows up and spot paint over them until the ship looks like a smooth block of aluminum. At this point you have a choice to make. You can if you are painting darker colors (not white or lemon yellow, pale blue or light green) use the silver as the block coat and start color after a light sanding with 600 wet or sand the silver down till there is only a hint on the surface and put a block coat of light gray or dania cream. Once this dries hard, lightly sand with 600 wet then go to you final colors.
Best, DennisT
w
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Roger,
Silver dope has been used by several top fliers as the first color coat to detect flaws. The idea is to get the substrate smooth and then spray on the silver. At this point you will likely have a good cry. The ship will have rough spots, dry spots, dings you thought you took care of. One tip is to use Brodak Silver. They worked on this to get a formula that dries hard in a day or so (SIG silver works but takes two weeks to dry per coat). Once dry start block sanding it off (hand sand on the open bay section and go slow so as not to sand through at the ribs). Once you get most of it off you will see the problem areas that you need to fix. Once those are addressed give the whole ship a final sanding with 420, wipe down with degreaser and give it a second coat. This time will not hurt as much, touch up whatever shows up and spot paint over them until the ship looks like a smooth block of aluminum. At this point you have a choice to make. You can if you are painting darker colors (not white or lemon yellow, pale blue or light green) use the silver as the block coat and start color after a light sanding with 600 wet or sand the silver down till there is only a hint on the surface and put a block coat of light gray or dania cream. Once this dries hard, lightly sand with 600 wet then go to you final colors.
Best, DennisT
w
I'm not sure why you are having such a long drying time between coats of Sig silver butyrate dope. Awhile back I recovered a full-scale 1939 Waco UPF-7 using the Ceconite process for a client using all Sig dope (the client had requested Sig & since I like Sig dope products I was happy to use it): from the clear through the silver through the color coats. In the morning I would spray on two coats of silver & wet sand it the next morning - it was plenty dry. I also use Sig butyrate dopes on my models & have never noticed any long dry times, whether it be clear, silver, or colors.
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Hi Bill,
I know you have used plenty of each, so what are your thoughts on comparing Sig butyrate to Randolph butyrate?
Thanks!
Bill
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Hi Bill,
I know you have used plenty of each, so what are your thoughts on comparing Sig butyrate to Randolph butyrate?
Thanks!
Bill
Hi Bill,
Sorry for the tardy reply but I just now got back to this topic.
In my experience over the years having used gallons of both Sig & Randolph, they are very equivalent in terms of compatibility with each other, ease of application, and drying times. I tend to use Randolph for colors because they have such a huge selection of colors compared with Sig, but I do use Sig colors if they have what I want. For the final clear butyrate topcoat I use Sig Light Coat as I have found it to be somewhat more fuel resistant than any other brand of clear.
Sig thinner is the slowest drying of the three I use, Randolph thinner is the next faster drying, and Certified is a little faster than Randolph. I blend the thinners to get the drying times I need (and occasionally use a bit of retarder.)
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Hi Bill,
Sorry for the tardy reply but I just now got back to this topic.
In my experience over the years having used gallons of both Sig & Randolph, they are very equivalent in terms of compatibility with each other, ease of application, and drying times. I tend to use Randolph for colors because they have such a huge selection of colors compared with Sig, but I do use Sig colors if they have what I want. For the final clear butyrate topcoat I use Sig Light Coat as I have found it to be somewhat more fuel resistant than any other brand of clear.
Sig thinner is the slowest drying of the three I use, Randolph thinner is the next faster drying, and Certified is a little faster than Randolph. I blend the thinners to get the drying times I need (and occasionally use a bit of retarder.)
Thanks, Bill. As to retarder, how much % do you figure is the top to use? On my last time using retarder, I used way too much. It softened the layers all the way to the wood! This would have been fine if i had known it and given it proper time to cure. But I was too fast and pulled up paint all the way down.
Bill
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Thanks, Bill. As to retarder, how much % do you figure is the top to use? On my last time using retarder, I used way too much. It softened the layers all the way to the wood! This would have been fine if i had known it and given it proper time to cure. But I was too fast and pulled up paint all the way down.
Bill
Hi Bill,
If I am going to use retarder in butyrate - of the total thinner used in a batch I would make the total retarder used to be a maximum of 10% of the total thinner mixed with the dope. In other words, if you are using a pint of unreduced butyrate to be thinned to 50% butyrate/50% thinner then make up a total of a pint of thinner/retarder with 10% of that being retarder.
Retarder is helpful under conditions of high humidity or high temperature, but there are some conditions that are just outside of the envelope of retarder to fix - you just have to wait for better conditions.
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Bill,
My comments on Sig silver are based on information from Windy and my own experience. Of all the paints silver and other metallic are the biggest pain when it comes to drying completely. By letting the silver really dry it sands smooth without clogging the sandpaper. You are located in S Ca so you may have local conditions that allow it to dry faster. Also the type of thinner plays a part in how fast it dries hard (Brodak is very fast, Sig as you said is very low), this may be the biggest factor in how long it takes to dry hard. The idea is to let the silver dry until it sands easy dry then sand it down with the wet 400 - 600.
I remember when Windy was doing some of the paint development for Brodak (which uses Randolph as the base and their thinner) he was very surprised at how fast the dope dried hard for buffing compared to Sig. It seems the reducer/thinner is the difference and should help any dope it is used in.
Best, DennisT