A quick question on blow-ins...

[chrissyo.]

So I've been doing these for a while now and I'm still having trouble deciding whether or not to plug up the blowtube of the "cup". When I do them ill have the cup opened up with the blowtube plugged with a stopper, drop in my bubble, blow, and while blowing take out the stopper so that the color reaches the whole point.. When I think about it now, that seems stupid and like a lot of fumbling about, which it sometimes can be. And i dont think i should be plugging becuase once i take it out and finish the puff, the remaing color dosent stick all the way and i end up with a whole lot of unwanted trapped air. I guess the reason i still do it like that is becuase the couple of times i did it w/o plugging, the color bubble didnt blow out even and got super thin at the tail end and popped. So my question is do you guys plug up the blowtube or not??

[Firekist]

don't plug it. maybe you change the heat you use a little, and how deeply you drop in your hot gather before puffing.. but.. don't plug it.

===seth

[FredLight]

So many points to fine tuning your blow-in.

I've found that I coil my color onto a collared blowtube to get it hot enough and not thin out at the top.

So, my prep is a piece of 9mm with a piece of 25mm (about an inch) at the open end. Coil off of that. It'll help support the blank you're blowing into,and it helps fill the gap between the 9mm tube and the 44mm or larger blank.

Also, I run my kiln slightly higher for preheating blanks for blow-ins. Cold blanks will give you disastrous air traps.

[chrissyo.]

Wordie, thanks guys., I think I'll give the bigger pre-heat a go too., I knew I was doing something wrong because people do solid color blowins and I know if i tried that I would probably end up with a third of the size I originally started with trying to save just the parts with no air.,. A lot of times ill still get little baby bubbles on what would be considered the best, most keeper part of the whole thing., But thanks for the replies!!

[Slow]

I do a lot of blow-in prodo, and I never plug the blowtube. Well, I do plug it so I can heat the inside of the blank in the flame, but I unplug it before blowing in the color. Once you get a good feel for the amount of heat and pressure you need, it's not that tricky to get the color from one end to the other without popping it. Something that someone once told me on this forum helped keep bubbles out of the blowtube end: where the blank meets the blowtube, you want a nice taper, not an abrupt change in diameter.

[Olorin]

My friend who taught me blow ins taught me this way: pull a point with a gradual taper at the end, then puff out/marver the closed end until the whole thing is a large cone shaped piece. I honestly didnt even know what questions to ask or anythign about blow ins when he taught me, but I've been doing them like that for a year ish now and they work really well...no bubbles as long as the lip of the open end is smooth. Hopefully this helps!

[FredLight]

^ Sounds like cup-stuff. Interesting.

My prep usually yields a soda can sized blow-in. A piece of 44mm about 6 inches long. I don't want to flare all that into a cone, but hey, I'm just a perpetual noob.

[justiceglass]

trapping a bit of air can make for some dramatic inside surface effects.. especially with striking colors.
:)

[gn0me]

One last tip - if you're not using a stainless blowtube for your color, use cobalt, green, or black tubing to coil onto. The extra stiffness lets you get the coilpot nice and hot without the blowtube going floppy as easily. If you are using a steel blowtube, you might want to coil on a little buffer glass before your color, since it can get all schmutzy from metal bits that come off the tube.

[cody]

You should deffenitly leave it open. I like to use 50x5 and to pull a point of not much more than 4in, otherwise I find the blowin gets too uneven if it's too big a chunck and leads to air bubbles. Also, I like to keep the opening on the point pretty small, really helps to keep the color from expanding or thining out into the point way fast, as I found it does if you have a big opening on the 50x5 chunck. Last tip, I like to use 25x4 to encase for the blowin. When I go to encase it I like to leave about 1/2in or so of the 25x4 un encased between what I colored and the blow tube. It helps to kinda act like a buffer so you can rage on the colored part without affecting the blow tube. Also, its nice to have the extra heavy wall there so when I'm melting it in on the blow tube end I can still rage it and get it nice even while basically only affecting the color tube