weird Petrobond sand recipe

Discussion in 'Sand Casting' started by HT1, Oct 11, 2020.

  1. Melterskelter

    Melterskelter Gold Banner Member

    It's from Petrobondoforsale. Standard stuff I guess.

    I actually posted the bave in the wrong thread. I intended it for the "Small Part, Great Casting" thread. I think I will put it there at the risk of a "Double posting" penalty.

    Denis
     
  2. HT1

    HT1 Silver Banner Member

    thats what I use though Mine is Quite old, I buy about 100 Lbs a year for makeup, yours is obviously newer, I have not seen orange in a year

    Thanks

    Ht1
     
  3. dennis

    dennis Silver Banner Member

    I recall him saying it was 140 mesh.

    That picture tells me plenty. I'll see about getting some as soon as can be managed.

    I have seen advertisements for Petrobond done with 190 mesh Olivine - at Amazon. Not sure if they still have it. It tended to sell out in a hurry.

    Teton-black. Will check at their web site this AM.

    https://www.tetonsupplyco.com/

    Nearly everything there is sold out.
     
    Last edited: Apr 4, 2021
  4. dennis

    dennis Silver Banner Member

    Speaking of Petrobond - what is a good parting compound?

    Calcium Carbonate?
    Talc?
    Graphite?
    Mixtures of these?
    A Commercial material?
     
  5. HT1

    HT1 Silver Banner Member

    pool filter diatomaceous earth

    about a $/ Lbs 25Lbs will last a lifetime

    can get it in any hardware store

    V/r HT1
     
  6. DavidF

    DavidF Administrator Staff Member Banner Member

    They have it at tractor supply...
    Great dust bath for chickens.
     
  7. DavidF

    DavidF Administrator Staff Member Banner Member

  8. Melterskelter

    Melterskelter Gold Banner Member

    Talc seems to work fine and is available at places that do or supply ceramic shops and workspaces. I just bought 5 pounds for 5 dollars. Graphite seems also to work very well as a parting compound. It is available for pretty cheap at Napa stores (oddly enough.) Overall I feel like Petro parts more easily than green sand.

    Denis
     
  9. HT1

    HT1 Silver Banner Member

    i would buy a small bag and try it,
    watch for the agricultural grade, it has bentonite in it and will NOT act as a parting

    I specifically use Pool filter DE its pure white

    Denis is right about talc , but you cannot just use baby powder (It's corn starch not talc ) and definitely not out of the bottle, must be shaken on from a muslin bag , from the bottle you will get lumps and Tobho mott has shown what that causes
    graphite works, but it is better for slicking up your pattern by working it onto the pattern, parting dust is meant to stay on the sand .

    I use both Graphite and parting


    White parting is also helpful to show damage in your mold when you pull the pattern, any loose sand pops on the white parting, not true on the black surface from graphite ( once your sand is all black from use , while its still orange, graphite works ok )


    Some one mentioned being able to get talc from billiard supplies ???


    V/r HT1
    P.S. Old school parting was silicia dust, probably want to avoid that
     
    dennis likes this.
  10. Melterskelter

    Melterskelter Gold Banner Member

    A few thoughts on graphite:

    I have been casually experimenting with talc purchased from a clay shop here in town and comparing it to graphite purchased from NAPA as a parting compound. Evidently talc is used in many glazes in the pottery world.

    My conclusion so far is that graphite is better than talc on green sand and is excellent on petro. I am not sure yet if it is better on petro, but I think it is.

    My suspicion is that graphite has a greasy quality that makes it harder for molding sand to penetrate the parting powder barrier and cause spalling of the cope onto the drag or vise versa.

    With respect to allowing release of sand from a pattern I can not see a difference. They both work fine.

    I think lightly brusing the parting dust, either talc or graphite, applied to a cope or drag surface improves it effectiveness. I am guessing this is because brushing it helps the parting find the spaces between sand grains and fill them in. I use a very soft and long-bristled brush to do the swirly-pattern brushing.

    I blow off excess parting on the pattern so that you can just see that there is a perceptible dullness to the surface but you really can't see actual accumulation of parting compound.

    With respect to the graphite not revealing parting defects in the sand: it is true that my green sand is black in color (some one of the thousand shades of "black") and the graphite is another shade of black. But the appearance of graphite is enough different and has a slightly more silvery and grey quality that for me to see said defects is not an issue. Yes, the talc being almost white highlights them so they can be seen from across the room. But at the bench I have not trouble seeing them with graphite. And petro provides pretty obvious contrast.

    Denis
     
  11. Tobho Mott

    Tobho Mott Gold Banner Member

    I think we can still get all talc baby powder up here, at least last time I looked they had 2 kinds, corn starch for a couple bucks more and real talc for a couple bucks less.

    Fwiw, I really like white parting dust. Makes it really easy to see when rapping on patterns starts to loosen them up - a tiny gap between the pattern and the sand at the parting line really stands against the white layer of parting.

    Jeff
     
  12. rocco

    rocco Silver

    I can confirm that. Most of the baby powder on the store shelves is corn starch but if you read the labels, you can still find talc, at least here in Canada you can.
     
  13. Jason

    Jason Gold

    I learned something about graphite last year with that electroforming stuff. Most graphite now a days is synthetic and if you want the real deal, you gotta dig deep in your wallet. I'm embarrassed to say what I had to pay for a small container of generals graphite. I dont know if it matters for casting, just something to be aware of if problems arise.;)
     
    dennis likes this.
  14. DavidF

    DavidF Administrator Staff Member Banner Member

  15. HT1

    HT1 Silver Banner Member

    Johnson & Johnson just paid 3.9 BILLION$ in a settlement, because they knew talc could cause ovarian cancer, so you will not see anything you sprinkle on your private parts containing talc anymore , that is why Billiards talc or DE
     
    Tobho Mott likes this.
  16. Jason

    Jason Gold

  17. The problem with talc is that it's similar to asbestos and the two are often found together in deposits so they have to be careful to keep the cancer causing asbestos out of the talc. For women the risk of ovarian cancer goes from 1.3% to 1.7% if using talcum powder.
     
  18. Melterskelter

    Melterskelter Gold Banner Member

    I was using graphite on petro today and decided to upload a few images. You will also see a little talc on the cope as I talced the pattern prior to packing the cope. Graphite1.JPG Graphite2.JPG Graphite3.JPG Graphite4.JPG

    OI like the way graphite behaves as a parting compound. I jsutr sieve it on and then brush it with a soft brush.

    Denis
     
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  19. Melterskelter

    Melterskelter Gold Banner Member

    What I bought from NAPA is listed as Natural Graphite. It is very finely ground and costs 30 bucks for 10 pounds. That amount will last a long time when used as parting powder.

    https://www.napaonline.com/en/p/BK_..._uoMueCYm4B8pjLYMt5UY7nhlg6WUghoCofIQAvD_BwE&

    I think it would also be available at farm suply stores (maybe cheaper) as the product is "intended" to be used as a dry lubricant for seed planting machines.

    Denis
     
  20. Jason

    Jason Gold

    I paid WAYY more than that! I need to check that out.
     

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