Never microwave the part in Alcohol. The alcohol absorbs into the material and will cause a reaction in itself.Alcohol is kind of detrimental both on the pdms and the B9 material. It does work as a first stage cleaner in an Ultrasonic.
Thicker pieces , the size you show need less microwave.
I will list the entire process so that it can be put on the wiki if others test it and it works .
Remove the part from the table:
1) clean prototype in Iso Alcohol with Ultrasonic. Other types of alcohol actually cause damage quickly. OR use dawn liquid dish washing soap in warm water (best in ultrasonic.) I prefer staying away from Alcohol.
2) put Mineral oil ( edible variety. CVS, Walgreens)in heat proof glass bowl . Pyrex or Dow corning...available at walmart and put the parts in the oil and into the Microwave.
3) Using 700 watt Microwave or lower wattage ( or adjustable) run it on the rotary table inside the microwave for 3 minutes. This will approach 300 0F the first time. after 10 minutes, the oil is still quite hot, so now you go another 3 minutes in the microwave. It could go higher/quicker with a more powerful Microwave. That is not desirable.
We know from Oven curing it must be done in stages to 345 degrees or so. With a microwave, It happens much quicker and if left too long or in a powerful Microwave, it will damage the pieces just like the oven does when you go directly in at high temp. That is why I suggest a 700 watt or lower Mic.
4) Pour oil back into the bottle using small plastic funnel. the parts will usually stay in the funnel. let them drip a while into the funnel. Use Air pressure to blast off most of the oil or Use Roberts Suggestion to heat dry the oil at (I believe he tried 150 oF) for an hour ( could be less time). Leaving excess oil did not seem to cause any ill effects.. it seems to absorb into the investment easily and may actually help the burn of the oil and resin
5) wax does not stick to oil easily, So I use my wax welder ( small soldering Iron with Variable light switch dimmer, very cheap!) I remove the resin base it was grown on and I weld a thin coating of wax onto the prototype where I will put the sprue. I do this so that I can really apply some heat to the wax so it actually mixes with the oil and dries into the B9 material. Now, I weld the sprue to that area. Works best with Bigger sprues as this will help the resin to leave.
6) Invest in any investment at it's strongest setting. Usually 38/100 ratio. I have tested on R&R Max and Plasticast. You can mix at 37/100 , but you will have to adjust your setting time. Let investment sit for 1 hour ( you can wait longer if you wish). With a programmable oven, raise the temperature to just below water boiling temperature . I use 200 oF for 3 hours.... then I ramp up to 1400 oF and I leave them at that temperature for at least 3 hours ( more time if you have a full oven). Then I ramp down to whatever my desired casting temperature is and cast after the temperature has settled in the flask.
7 Follow whatever procedure you do after casting.