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myersbw
member
Reged: 04/30/09
Posts: 10
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I'm experimenting with some casual small refractor builds (copyscope, etc.) and using PVC for the tube. Can anyone think of a reason why roofing tar paper shouldn't be used as an inside liner? It's a nice textured flat black...I popped a piece in once and it was a quick fix. I can't think of any compositional breakdown issues over time....comments?
Thanks!
Brad
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skypilgrim
professor emeritus
Reged: 12/25/06
Posts: 558
Loc: Under a cloud
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Out-gassing?
Just a guess. The roofing paper I've used was quite aromatic so I'd wonder what it'd do to lens coatings, etc.
Sam
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AL Messier certificate #2078
AL Double Star certificate #354
Area of interest: Cultural Astronomy
My Blog: http://fathersky.wordpress.com/
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myersbw
member
Reged: 04/30/09
Posts: 10
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Yeah, I was curious about that, but I wasn't certain.
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rboe
Reged: 03/16/02
Posts: 45411
Loc: Phx, AZ
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Ya, outgassing was my first thought too. Avoid it. Plenty of other choices to even consider this one.
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Ron
NS11GPS
Pronto
16" dob
15X70 Obies
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PitchHitter
member
Reged: 09/23/09
Posts: 23
Loc: Southern Sierras
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Yes, in the closed tube the oils will go to the glass. I came across an old phenolic tubed telescope that seened to be made of tar paper and resin. The oils made a hard to clean mess. Besides the paper does break down. If left in the sun it turns a dark gray as it loses its oil and looks like faded felt paper. It is also not so "flat" at steep incedence angles.
Baffles are needed for refractors anyway. I cut mine out of left over pot pie plates.
Good Luck,
Rick
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About 20 telescopes from a 200mmAPO up
Fav is Meade 10" f:4.5 using my 3" 40mm 96°AFOV
BUT! In Progress:
14.5" f:5 grab n' go with DSCs will offer 2.4 degrees at 45 power and 8mm exit pupil (Light Bridge Buster)
16.25" f:7.5 to refigure
(20th wave ruined in a fire at the coaters)
22" f5: New mount almost done
(old all aluminum mount was stolen)
16" Varian Vapor Deposition Coater.
Looking for larger chamber.
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