Blanks too hard

**turnerted** · 5th November 2014, 12:00 PM

G'day
You may remember some time ago I posted pictures of bangles I have been casting with gumnuts and other inclusions.
I decided it was time I tried making some pen blanks with inclusions, in this case,sheoke cones which I have used before .I used the same polyester casting resin that I used for my bangles but I decided to add a bit of pigment . I used a "pillarbox red" polyester red pigment which I think came from "Fibre Glass International".I didn't measure the volume of pigment I used ,but it was probably about 1gm in 230gm of resin.I used 2% catylist and did my casting in a preasure pot.Gel time as judged by the residue in the mixing jug,was about 20 minutes . I left it overnight and popped it out the next day . The only difference I noticed to my previous castings, was that it did not have the slightly tacky surface I am used to.I cut the slab up into pen blanks and attempted to turn a pen then discovered how hard the resin was . I tried a bowl gouge , a skew and a negative rake scrapper but was unable to get the filamentous shavings I am used to from polyester . After about 1/2 an hour and frequent trips to the grinder, I barely had the blank down to round.
So my question is, can pigment make a difference to the hardness of a casting as that seems to be the only thing I have done differently?
I look forward to comments from the experts.
Ted

**tdrumnut** · 6th November 2014, 12:21 PM

2% catalyst seems to much to me. I use between 0.5 & 1% catalyst as I find the quicker the resin dries the more brittle the end result and there is also less chance of cracking. If you are leaving in the pot over night then I would suggest cutting back on the catalyst.

**dai sensei** · 7th November 2014, 12:03 PM

Yes cast items are hard, but the variations between the cast items and the resin components will blunt your tools quickly. I always sand my blanks round before turning, in fact sand them to within 2mm if possible, using either the disc sander by hand or a flap sander (my new roughing gouge

) whilst on mandrel

**turnerted** · 7th November 2014, 04:28 PM

Thanks for the replys.My next move was going to be to attack it with the angle grinder.
If succesful I'll post the results .
Ted

**turnerted** · 10th November 2014, 04:22 PM

Success . Following Neil's suggestion , I used my 60 grit angle grinder roughing gouge , then finished shaping with a scraper . This not a technique I would like to use without a dust extractor and PP respirator but it worked well .
I finished off with CA , micromesh , EEE then Shellawax.The result was so good ,I cast another slab ,this time of gumnuts . This was a little more work , as there were a few voids .I filled them with five minute epoxy with a speck of pigment added and after a couple of hours skimmed the suface with a skew and finished as above .
Sorry the picture is a bit dark.Someone who knows how is welcome to lighten it .
Comments welcome.
Ted

**Christos** · 10th November 2014, 04:32 PM

I am currently using a computer that hopefully has lighten the photo up a little.

100_1469.jpg

**turnerted** · 11th November 2014, 12:05 PM

Thanks Christos . That has improved it a bit . It was actually photographed against a white background but shows up as blue . The reflection must have really thrown out the exposure and colour balance.
Ted

**dai sensei** · 11th November 2014, 01:00 PM

Here's the best I can do

temp.jpg

**turnerted** · 11th November 2014, 03:55 PM

Thats looking good now Neil.Thanks
Ted

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