Originally Posted by
kevin c
OK, new to casting, new to HiTek. What I've done so far works great, but a few questions to those in the know. Do I need a new oven (I think so)? Is a little wipe off from the Black Cherry OK?
I used Rotometals hardball to eliminate alloy concerns. Finally I am getting the hang of using my slick side 147 grain molds from Accurate. I'm using the HiTek release. Two coats of Black Cherry, mixed with a weighed 20 grams to a measured 120 ml acetone (reading the thread [all of it, twice], I got the impression that 20 to 100 was the equivalent of 5-1-5 of the liquid, and wanted to match the 5-1-7 that Ausglock was using). The mix was left to stand to react. Had a couple reject bullets in the container for agitation. Used a long tube on a syringe to pull up the solution from the middle of the bottle, but didn't delay after shaking. 6 ml on 5# of casts, shaken in a closed container for about 20 seconds, another 5 or so with the lid off, dumped on mesh before the sound change but with the container not wet. Dried over night.
20 grams to 120 mil is generally used durring hotter weather, you can also substitute 20 mil M.E.K. or Denatured alcohol to slow down the drying time.
Quote Originally Posted by Ausglock
Did a bit of testing over the weekend.
1st coat was 4mls to 2.5Kg.
second coat 6mls to 2.5Kg.
This resulted in a far shinier finish and no visible touch marks.
time and temp remained the same as did the mix ratio. Your first coat could have been to thick
The oven is a 15 dollar used convection toaster oven. Temp measured via K probe on a DVOM, preheated, and with the probe left in the oven during the bake. Bake times ran 12 to 22 minutes for each of the two coats.
if the oven is reaching 200 / 400 degrees 22 min is excessive I would doubled check the temperature, your K probe could be off (it happens but not often. I like to use 2 oven thermometers set in the middle of the shelf I bake on and adjust the oven setting until the 2 thermometers reach 200 / 400 IF the 2 thermometers don't match, get a third to find 2 that match. Many controls the oven with a PID, I haven't found the need. If you do decide to use a PID you should wire the circulating fan to be on perminantly of you'll burn it out. Another "trick is to line the bottom of your oven with heat retaining media, I use ceramic BBQ briquettes, others use fire brick, metal plate ... this helps get the oven back to temperature faster after opening the door
The reason for the prolonged bake times was that I kept getting wipe off. Not a lot, but a little, that only went away when the bake time hit 20 minutes. Despite having the probe verify the temp (200 to 205 C through out the bake), the bullets did not darken much at all - I got the nice cherry color that is shown in the photos in post 8595. All smash tests fine, and no leading through my Glock factory barrels.
So I am very happy with the HiTek, but am wondering about the long bake times. I did note that the temps I got were with the probe right over the tray, but with the probe just under the mesh tray it was 20 degrees cooler. The fan seemed to work, but I don't know just how much the temp should vary vertically in a convection oven.
I read that some of the powders were color saturated - could that explain the wipe off? I also read comments that maybe the powder components can separate. I didn't shake up the dry powder before measuring it out.
New oven (Breville) on the way. Any comments/suggestions? TIA