Tobho's HT1-Inspired Cement Mixer Muller Build

Discussion in 'Sand Mullers' started by Tobho Mott, Mar 22, 2018.

  1. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Wow, heat really softens up the hard packed petrobond, HT1 was right again. I tried mulling the sand right after shaking out a couple of molds and making sure to put in no more than half a 5 gallon bucket at a time. The broken up chunks of mold just kinda squished apart when I poked at them a little, so there were no hard clods to jam up the muller. Worked great. And OMG I love this sand!

    20201119_154304_copy_1040x520.jpg

    Hey HT1, if you do record a petrobond mulling video this weekend, it would be great to see how much sand, alcohol, and oil (if any) goes into the muller for each load.

    Jeff
     
    dennis likes this.
  2. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    This guy dilutes his 91% alcohol 50/50 with water, maybe I can just use rubbing alcohol from any drug store or walmart, I think it's like 70% or something.



    What does the alcohol do anyhow, is it somehow related to the catalyst I've read is needed to make new petrobond?

    Jeff
     
  3. HT1

    HT1 Gold Banner Member

    alcohol is a substitute for for catalyst , you can buy 70 or 90% here is exactlry what i use
    https://www.walmart.com/ip/Equate-91-Isopropyl-Alcohol-Antiseptic-32-fl-oz/276040459

    i have heard about using watered down Alcohol, I have no idea where the Idea that came from
    but from this patent
    https://patents.google.com/patent/US6669770B1/en

    "Suitable catalysts include that known as “P1 Catalyst” provided by Bentonite Performance Materials which is a propylene carbonate. Similarly methyl hydrate is known to serve as a catalyst."

    Rubbing Algohol is chemically very similiar to both these compounds

    Here is p-1's MSDS https://msds.halliburton.com/msdsdo...oader/Document?prd=HM005247~~PDF~~MTR~~US~~EN

    Reconditioning your sand:
    1)Get an oil squirt can for the oil
    2) a spray bottle for the alcohol I use the upside down bottle from tractor supply

    oil burns out in use , if you see smoke you burn't out oil, you need more catalyst to get the oil to react with the clay
    how much oil to add ( It depend on how much you burnt out ) big heavy castings , will leave lots of burnt sand , you can see this, it will be grey, if you do cast Fe it will be a solid layer possibly stuck to your casting, if you do cast Fe in petrobond seriously consider throwing out the grey/white sand . with Brass/bronze or aluminum dont worry about it,

    for aluminum, I add NO oil, and just mist the sand with Alcohol , the Alcohol seems ( this is just my observation no science here) to make the sand "fluffy" and it will mull better, in the Professional foundry about every third time we mulleed we would power riddle the sand after mulling which makes it very fluffy and gets all but the smallest bits of burnt sand .

    Lets talk for just a second about fluffy while not a technical term if you ever get to aeriate or power riddle sand this term is really understandable, the sand all but doubles in volume and flows really well, but takes more effort to ram , if you store the sand , it will settle out alot


    For Brass, I add about two squirts of oil per muller load , and 3 mists of alcohol remember the longer you mull the better your green strength, though there are diminishibng returns 11 minutes is the longest practicable time to mull, I shoot for half that


    keepiing in mind my 12X12 flasks I add about one half a mold to the Muller and call it a load so most pours make me run 20 loads through the muller , so i mull about 1.5 hours after casting

    V/r HT1
     
  4. rocco

    rocco Silver

    Methyl hydrate is cheaper than rubbing alcohol and easy enough to find so why mess around with rubbing alcohol at all?
     
    Tobho Mott likes this.
  5. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Thanks for the specifics HT1.

    $10 for 3.78L of 99.9% methyl hydrate at Canadian Tire. Good deal. That ought to last a while!

    Jeff
     
  6. rocco

    rocco Silver

    I could be mistaken but I vaguely remember something about methyl hydrate being capable of being absorbed through the skin, maybe look up the MSDS to make sure you use it safely.
     
    dennis likes this.
  7. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Hmm, rubbing alcohol you say...
     
  8. Melterskelter

    Melterskelter Gold Banner Member

    Otherwise known as wood alcohol or methanol. Never heard of trouble topically. Not good for drinking though.:eek:

    Denis
     
    Tobho Mott likes this.
  9. rocco

    rocco Silver

    Just looked it up, the MSDS for methyl hydrate says to avoid drinking it, inhaling it or getting it on your skin. FWIW, the MSDS for isopropyl (rubbing) alcohol is similar it says to avoid, drinking it, inhaling it, or prolonged contact with skin. Either way, it's no big deal, just be aware and take appropriate measures to protect yourself. "Better safe than stupid"
     
  10. HT1

    HT1 Gold Banner Member

    here is my muller running Petrobond , Hot petrobond from Brass molds about 2 hours old




    here is a closeup of my blades the blade at the top of the muller catches sand after the wheel and puses it towards the center, the lower blade catches any sand in the center of the muller and directs it outward, while its other side directs sand directly under the wheel
    IMG_4260.jpg

    you can see in the video, that ALOT of the mulling action actually happens betweeen the trailing edge og the wheel , and the wall of the muller, this was not intentional, but it certainly works , BTW that wheel is from Harbor freight, I have replaced it once or twice like $16 (bearings) i used to have a 10Lb Lead weight on the Wheel, it broke off, I have never welded it back on (shrug)

    V/r HT1
     
    Tobho Mott likes this.
  11. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Much appreciated, thanks.

    Jeff
     
  12. I have tried a few things with mine and have been using HEET fuel additive now. you dont need much, keeping it in the muller for 10-15 min really does an amazing job at getting it back to near new even if its completely black from getting burned out. I have never had to add more petrobond clay to mine and have used it for 100+ bronze casts. I try to pull the parts after about 5 min cooling time and stamp out the sand so less burns up.

    New petrobond 2 does not need any catalyst.
     
    Tobho Mott likes this.
  13. rocco

    rocco Silver

    FWIW, according to its msds, HEET fuel additive is 99% methanol and 1% other proprietary ingredients. They also make iso-HEET fuel additive which is 98.5% isopropyl alcohol.
     
    Tobho Mott likes this.
  14. HT1

    HT1 Gold Banner Member


    The only reason to add Clay is having added too much oil, I had this issue, before I switched to the oil squirt can and was just pouring oil in to my tiny muller ,

    the problem that will eventually develop is the fines (crushed sand) will lower permiability, and you will begin to get gas related issues , in the Hobby setting this could be YEARS down the road or never,
    be prepared though as the cure is to replace all your sand

    V/r HT1
     
    dennis likes this.
  15. dennis

    dennis Silver

    Whereupon it is metabolized into formaldehyde...

    I knew someone whose father died from contact with this stuff, though I think he said it was due to long-term exposure... (45 years ago or so.)

    Seems he was right: https://www.google.com/url?sa=t&sou...FjABegQICBAE&usg=AOvVaw3uQwoKqsWLxqns8cC9mGBQ
     
  16. Melterskelter

    Melterskelter Gold Banner Member

    And ethanol that so many DRINK is also metabolized into formaldehyde. Sounds scary to note the formaldehyde connection. I well remember someone rather self-righteously raising a question about my use of a photochemical listed as possibly carcinogenic. This was at a dinner where most people including this guy were drinking wine and beer. He looked a little shocked when I pointed out to him that ethanol is listed as a known carcinogen. I told him that at least I did not drink the stuff!


    upload_2021-1-8_8-22-6.png

    The chemical formula for ethanol is C2H6O whereas the formula for methanol is CH4O. Alcohol dehydrogenase converts methanol into formaldehyde (CH2O) and aldehyde dehydrogenase turns this formaldehyde into a formic acid radical (CH2O-).

    Denis
     
    dennis likes this.
  17. dennis

    dennis Silver

    The radical is the carcinogen - or is it?

    Acetaldehyde doesn't sound healthy, either - over and above the nightmare/flashback-inducing way it makes people smell. (To me, anyway.)

    I'll stick with rubbing alcohol when I (finally!) get my (itching) hands on some Petrobond - unless I can get propylene carbonate easily/cheaply.

    Amazon has this stuff, but it's pushing 37$ a quart shipped!
     
    Last edited: Jan 8, 2021
  18. Melterskelter

    Melterskelter Gold Banner Member

    That question is above my paygrade. The human body metabolism is so complex that it usually impossible to pin down a chemical/drug action to a single metabolic alteration or step. Observation and large scale controlled and careful studies allow determination of net actions. But individual steps and their effects----harder. Quoting the existence of a scary sounding metabolic step and attributing it special significance is treacherous ground.

    Denis
     
  19. Melterskelter

    Melterskelter Gold Banner Member

    I bought propylene carbonate a while back in bulk from a refractrory supplier in your backyard---Portland. It was not OCL. But OCL might have it now sincew they bought out a supplier in Portland---details are fuzzy now. But may be worth a couple calls. Gabriella at OCL is a good contact person.

    Denis
     
  20. dennis

    dennis Silver

    Thanks. OCL is about 5 miles from me.
     

Share This Page