Hi Everyone!

I'm new to working with polymers.

A problem I have ~ after baking, my beads will often crack  when i am stringing them , or when I am sanding etc.

Are there any Do Nots?

Can different clays be mixed together, such as Kato & Sculpey?

Thanks for replies!

It would help if you explained how you make your beads (by hand or roller, how big, how long your baking, etc) and what material/brand you use. Billie

Hi Billie,

Thanks for replying :)

I use Kato, Sculpey & Premo Sculpey.

I bake at the suggested temps for all, & when I mix, I will bake at a mid temp:  if Kato is 350 for 15

mins & Sculpey is 275 for 30 mins. ~ I usually bake at say, 300 for 20 mins.

I was thinking that it may have to do with the conditioning process??

Maeve

I forgot to say, that I usually shape by hand , sometimes a mould.

 it's perfectly ok to blend brands of clay, my recommendation is to bake at 275 for an hour. 20 minutes may be too little for what you are doing. an hour is not really necessary but I do it just to make sure I am covered if there were any times the oven went below temp. Kato's temp is higher, but I've been told it cures fine at 275, just not as super strong. make sure your clay is well-conditioned too.

I haven't experienced this problem with Kato or with Premo!   I have heard regular Sculpey can be pretty fragile, but I've never used it, just the Premo! Sculpey.  If anything, I find the Premo!  kind of soft and flexible, not brittle at all.  Are you making the stringing holes big enough?  Is the clay conditioned and pressed firmly together?  Do the crack occur along lines where colors are blended or just randomly?  What do you use to sand?  Kato can be a pain to condition and I'm not sure what happens if you cure it if it isn't fully "plastic" but still crumbly in the raw state.

Thanks for all of your answers!

I've been thinking them over, and from all the comments I think I am doing 2 things wrong.

!) I've been rolling my clay out too thin ~ wafer thin...

2) with thicker beads, I have been making the holes much too small, so they don't stand up to being strung.

I'm working on a new bead set so I'll see how that goes~

Thanks again!

Sculpey is really too brittle for MOST  jewelry, depending on what you're doing,  but I think your biggest problem might actually be not conditioning the clay enough.  Even if it feels soft and pliable, the plasticiser may not be thoroughtly incorporated into the clay so try conditioning it more, especially Kato.  Once it's conditioned, Premo will be O.K. for several days or longer but Kato is best used right away, especially black for some reason, otherwise it needs to be reconditioned.  It doesn't matter what method you use to form the beads or focals - the method is not your problem.   

Some kinds of stringing wire can actually "saw" around the holes eventually, depending on how much wear the jewelry gets.  If you are making flat pendants with hole from front to back, make them big enough for a jump ring so you won't have that problem.  If you are making pendants that will be strung side to side, make sure the clay is pretty thick (two layers of a medium setting on your pasta machine - ish).  And if it's regular beads, as long as the holes are big enough for stringing wire you're O.K.  If you make big hole beads intended for use with, say 18g or 16g wire, don't string them with stringing wire because they won't stay straight on the thin wire and the movement is likely to cause damage around the holes.  

Thanks Jilla & all,

Now I know why my preconditioned Kato is rock hard when I go to use it!!

I made a new batch of beads with all your suggestions in mind & they came out very well.

I drilled them after baking & no cracks!!!

So, a big THANK YOU to all ~

Hope I can help you out someday.