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I make mine with 1 layer insulbright and 1 layer w & w - have never had a problem! I also use this mix for mug rugs so the heat from coffee doesn't mark the furniture.
I double the insulbrite in the holder and use 4 layers in the mitt.
"Life's tragedy is that we get old too soon and wise too late".
'At least one layer of cotton batting is recommended with Insul~Bright when used as Oven Mitts or Pot Holders. Insul~Bright is heat-RESISTANT, NOT heat-proof.'
This is a quote from the Insul-bright website.
Quilts,Books,and Wine,Oh My!
I have never used insulbrite. I make potholder innards out of old shrunken sweaters (wool) and bits of towel (double layer).
Embroidery library has a tutorial on this they use insulbright and the shiny fabric that goes on ironning board covers. Yes, they make theirs using embroidery but the concept is still the same.
To remove items from the oven, I now use Ov Gloves. They keep this klutz (one thanksgiving I got 5 stitches cutting butter with a knife), they are made from kefvlar (sp???) if you can kefvlar fabric, I would recommend using that as a filler.
If life gives you lemons, make a margarita.
http://www.warmcompany.com/pdfs/ibeng.pdf I make mine to this pattern but the lining fabric is a good quality calico, which I use heaps of for not only these but backing for place-mats and linings for heavy duty totes.
My mother sent me a hand mit for the oven and it's like having a think piece of cloth on when I take something out of the oven. Talk about almost burning my fingers! She used felt - so that material doesn't work. I think when I make some oven mits or pot holders, I'll use something a little more heat resistant.
I also use old towels in hot pads. I usually use 2 or 3 layers and it seems to work fine.