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cold working by hand

Posted: Thu Mar 07, 2013 4:29 pm
by Delberta D
Can anyone give me an idea of time I would be looking at for cold working a flat piece about 12" square by using diamond hand pads? Probably just the top side and edge. Am I looking at sanding for a continuous hour, or am I looking at 3 hours? or more? I have 60, 200, and 800 grit diamond pads. (I thought maybe I would skip the 60) I really like the cold worked look but just can't spring for the equipment and plumbing right now. Also I have tripoli do I need cerium oxide? I may like the satin look when I get that far. I am then going to slump it in to a bowl. Your help would be very much appreciated, I have learned so much on here and I thank you all for ALL of your given information.

Re: cold working by hand

Posted: Thu Mar 07, 2013 5:55 pm
by Brock
Don't skip the 60 step, you need to flatten the piece before you can polish. I can't really give you a time, but probably longer than you would think. 200 to 800 is a big jump. I would achieve a good 200, then slump, it's a nice finish.

Re: cold working by hand

Posted: Thu Mar 07, 2013 10:23 pm
by Delberta D
Thank You Brock. I was afraid the 60 would make too deep of scratches....Soooo I am guessing I wouldn't want to do a whole set of 8 items by hand....??? They are for myself and I am not trying to sell them.

Re: cold working by hand

Posted: Mon Mar 11, 2013 4:16 pm
by Jerrwel
Searching the archives without success for a thread where coldworking with wet/dry sandpaper was discussed that seems appropriate for this discussion; there was a mention of an oil used to prolong the life of the sandpaper. Thought I had a 'favorite' for the topic, but can't find it and it is driving me (just the small distance that is required) crazy!!!!! Anyone remember the name of the oil especially?

OK, found the topic I was looking for: http://www.warmglass.com/phpBB/viewtopi ... ilit=large

And the polishing oil discussed within that topic: http://www.crlaurence.com/crlapps/showl ... elID=13754

Re: cold working by hand

Posted: Tue Mar 12, 2013 10:42 pm
by Delberta D
Thank you Jerry, an interesting concept, I would not have thought of grinding glass dry at all. I am sure I have seen one of these in my husbands tools....hmmm, I shall try it but I do realize I can only sand a little at a time so it doesn't get too hot. Thank you...Delberta

Re: cold working by hand

Posted: Wed Mar 13, 2013 12:25 am
by Morganica
I've used both oil and water, really don't see a lot of difference. The grit stays sharp a bit longer but seems to clog faster with the oil. The water gives a softer cut but doesn't clog as much, probably because you don't dip in the oil as much as you do the water.

Here's what I do: Get a thin sponge, wrap wet-dry sandpaper around it (or buy the little diamond sponges that HIS sells, they're not very expensive), 2 bath towels, a jellyroll pan or baking dish and a little bowl of water. Pop a movie in the player, plop down on the sofa with one towel on my lap and the other in the jelly roll pan. I put the glass in the pan, dip the sponge in the water, and go to town. ;-)

The sponge helps push the grit into the glass, speeding up the process, and it makes sanding a bit easier on the hands. If I start at 80-grit and move through to 600, I can sand a 4x6 inch bowl in about a movie and a half.

60-200-800 would be a LOT of work. You work fastest by moving up the grit levels in easy stages. It's not a huge deal to machine-sand 200 grit to an 800 finish, just takes a very long time and uses up a bunch of sandpaper...but if you're trying to do that by hand you will be very tired by the time you finish. 800-grit paper is removing very little material, so you'll be sanding and sanding to achieve what 400 grit would do very quickly.

I only use 60 if I've got a lot of shaping to do--it's just too much trouble otherwise to remove all the scratches. Otherwise, I start at 120, move to 220, then to 400. At 400 I'm probably done, at least if I'm fire polishing--that will give a soft to full gloss depending on your schedule. If I choose to seal the finish at 400 it will look like the average sandblast.

If I keep going to 600, I'll get a very silky-satin finish that glows softly when sealed and feels wonderful. If I firepolish it, it will be a full, rich gloss at high slumping temperatures. At 800, the glass is beginning to shine on its own--this piece was taken to 800-grit in about two movies.



I'd recommend picking up Paul Tarlow's book, Coldworking Glass without Machines.

Re: cold working by hand

Posted: Fri Mar 15, 2013 12:53 pm
by Delberta D
Thank you very much for all of that information. A few months ago I did purchase the book ' Coldworking glass without machines' but there was no real indication of time it takes from my reading. I am curious when you mentioned sealing the glass what you did to seal it. And the photo you put on is beautiful, I am thinking you had to sand this first and then slump or cast? I really like the finish you have on it. But if you slumped or cast after sanding then it would pick up mold texture...? Looks very pretty! And a lot of work. I think I will try a small piece with the wet dry sand paper. Since I don't have 400 grit diamond pads would it work to go from diamond pad to wet dry paper? I love your work, Thank You very much for your help...Delberta

Re: cold working by hand

Posted: Fri Mar 15, 2013 2:17 pm
by Morganica
Well, as I said, I measure hand-sanding time by movie, and a movie is anywhere from 1.5 to 2 hours or so. So a two-movie piece probably took 4 hours. ;-)

The piece in the photo is cast using the pate de verre process with powder on the surface. Powdered glass in a damp mold tends to result in a mild scum/devit that requires smoothing off, i.e., a light sanding. On this particular piece I had some mild flashing, and I do typically use sculpture tools for that (i.e., a Foredom grinder with 200-grit diamond bits). The hand-sanding process is both to remove the scum and equalize the ground surface with the rest of the piece, and that's the part that took two hours.

But honestly, it's really difficult to say how long it will take. It depends on the size of the piece, the condition when you start, the type of surface you're looking for and how perfect you need it to be, the grits you're using (I find it's generally faster to gradually step down grit sizes in sequence than to jump a couple hundred grit in one go), and your own technique.

On the sealer, you'll find a lot about this if you search the archives. I use one discovered by Jeff Wright, Unelko's shower sealer gel. You rub a very little of it onto the piece with a lint-free rag and work it in. It'll start out with a glossy shine that fades into a softer finish in a couple of weeks. It brings the color back to the glass without needing constant renewal.

Re: cold working by hand

Posted: Fri Mar 15, 2013 2:30 pm
by Brock
. . . Well, as I said, I measure hand-sanding time by movie, and a movie is anywhere from 1.5 to 2 hours or so. So a two-movie piece probably took 4 hours. ;-)

Hmmm . . . I measure airline travel by movies.
Vancouver-New Zealand is 6 movies and 4 rugby games.
Love those hakas . . .

Re: cold working by hand

Posted: Sun Mar 17, 2013 10:34 am
by Delberta D
Thank You, you have given me a very good idea on how long it would take. And thank you for the sealer information too!