devitrification on certain size.

[praspekt]

i've been playing around with different sizes of tubing lately, i ordered one piece of various sized tubing.. i've notices that the 34 x 2.8 has a lot of issues with devitrification. i really like the size though, good for i/o work, lots of depth.. it's also the biggest size that i've used.. is devitrification common on the larger sized tubes? i also got some 38 x 2.8, not sure what i'm going to do with it yet, maybe some bubblers..

maybe it's the one tube i got, cause i've never had it happen as bad as it down with the one particular size. what would cause this to happen in the makeup of the glass, for devitrification to be common?

what size tubing do you mostly use, and what do you make with it?

thanks!

[glassblowingBiker]

im going to go with seeing hows this is your first time with it that you are moveing it to cold get it white hot and shape it and you should have no porblem with devit Peace

[LTD]

wetter is better

[Firekist]

32x4 bats
38x2.8 spoons, sleeve for blue 25.4x4 tube sections.. make anything besides bats
38x4 spoons, sherlocks, sleeve for blue 25.4x4 tube sections.. make anything besides bats
44x4 sherlocks, sidecars, hammers, bubs
50x1.8 frit bats, frit fish
50x5 tube pulls
50x2 sleeve for 44x4 blue tube.. make anything besides bats

i've never noticed more devit with a particular tube, though i have had it. generally the tube pulls get sensitive to devit, but i think that's because they are in the flame WAY WAY more by the time they're done than anything else.. but that's just cause of the techs used.

not cleaning your tubes can lead to something like devit. a funky spot in the batch as they're pulling tubes could cause problems, but i doubt that'd happen often. small scratches can lead to problems like devit. overworking is usually the problem, along with excessive marvering while super hot.. apparently.

hope that helps... z0-0----seth

[praspekt]

thanks!! maybe it's because i'm not working it hot enough, cause it only happen when i melt down the neck of a pipe and pull out a bit.. i'll just work it a bit hotter.. although if it does happen i just re heat in a hot oxidizing flame till it's gone, it's just that with this 34 x 2.8 after i reheat it the devitrification comes back..

firekist, you must be making some big pieces!! for bats i usually use 24 x 2 or 26 x 2.8, for serlocks same size as well as spoons.. although i've only been blowing glass for 6 months now, so i've been sticking with smaller stuff, cheaper, and easier to work with i guess.. since i've started making spoons with the 34 x 2.8 i'm loving that size. for your average spoon, or sherlock, how long of a section of glass do you use? do you have any of your stuff online somewhere??

[Firekist]

not to bring up the debate, but i never call the wrinkles you can firepolish out devit.. since calling it devit gets people confused. i don't care if it is, or if it isn't.

anyway.. most of my work is thick... about 3.5 inches of 38x2.8 for my smallest i/o spoons. if i'm doing inside out work, i try not to use points bigger than 5 inches. i try to up the diameter and thickness before upping length. longer points are harder to inflate for how i work.

um.. www.glasspipes.org/zlao and www.glassartists.org/zlao

z---seth

[praspekt]

but isn't that what devitrificaion is by definition? what do you consider devitrification?? i checked out your work, very nice man!!

[Firekist]

de·vit·ri·fy
tr.v. de·vit·ri·fied, de·vit·ri·fy·ing, de·vit·ri·fies

To cause (a glassy material) to become crystalline and brittle.

so i guess when you move glass when it's "at that right temperature" and you get wrinkles, it's technicallly devitrification because you've caused the glass atoms to arrange in a crystalline lattice. flame polish, it's gone.. no real reason to talk about it imo.

when you overwork glass, you can get a similar looking hazy scummy look on clear, that feels rough to the touch. this will not flame polish out, it'll just get worse/spread. this, i think, happens because the flame has basically vaporized elements of the glass, and this surface layer of different glass behaves differently.. and.. it's scummy/rough/hazy whatever. maybe this is phase separation and not devitrification.. i really am not sure, and i really don't know who'd answer i'd even listen to/trust.
i do know people talk about flame polishable devit, and non flame polishable devit on the board, but just call both "devit".. which just leads to miscommunications.

so.. um... i hope this doesn't start into yet another "i thought devit was..." threads. i really don't care. if anyone has some good scientific papers on the matter to refer me to, that'd be great.

z--seth (thanks)