Author Topic: Petrobond moulding sand  (Read 1347 times)

Offline smiffy

  • Full Member
  • ***
  • Posts: 167
  • Country: gb
Petrobond moulding sand
« on: February 26, 2022, 12:00:24 PM »
I have 60 kgs of petrobond sand that needs rejuvenating .I have looked on the net for means of doing this and get conflicting advice . Has anyone done this and what method did you use ,or should I bin it and use green sand  Mike


Offline djc

  • Jr. Member
  • **
  • Posts: 77
Re: Petrobond moulding sand
« Reply #1 on: February 26, 2022, 01:57:02 PM »
This document, which originates from Petrobond itself (Google 'free slideshare cownloader' to obtain in pdf), suggests you just add a dollop of their magic snake oil and re-Mull (bagpipes optional). See also second link, which appears to be the manufacturer.

https://www.slideshare.net/FoundryJoe/petro-bond-foundry-sand-brochure
http://smelko.com/?page_id=322

Offline smiffy

  • Full Member
  • ***
  • Posts: 167
  • Country: gb
Re: Petrobond moulding sand
« Reply #2 on: February 26, 2022, 02:32:19 PM »
Thanks for the links . Several youtube videos suggest using  sae 30 straight engine oil , would that work to replace their snake oil, also adding some methanol is recommended . As I have not used petrobond before not sure whether this will work .Any ideas welcome Mike

Offline vtsteam

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 6363
  • Country: us
  • Republic of Vermont
Re: Petrobond moulding sand
« Reply #3 on: February 26, 2022, 07:01:05 PM »
Sorry I can't help. I just use greensand.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline WeldingRod

  • Sr. Member
  • ****
  • Posts: 395
Re: Petrobond moulding sand
« Reply #4 on: February 26, 2022, 10:01:29 PM »
Great stuff, but I haven't had to change the oil on mine yet ;-)

Sent from my SM-G715A using Tapatalk


Offline hermetic

  • Hero Member
  • *****
  • Posts: 673
  • Country: england
Re: Petrobond moulding sand
« Reply #5 on: February 28, 2022, 06:29:11 AM »
If you look on youtube at some of the small foundries in India, you will see them adding waste oil to sand!
Man who says it cannot be done should not disturb man doing it! https://www.youtube.com/user/philhermetic/videos?

Offline smiffy

  • Full Member
  • ***
  • Posts: 167
  • Country: gb
Re: Petrobond moulding sand
« Reply #6 on: March 01, 2022, 08:48:38 AM »
Today I went to a small foundry in Stourbridge as I wanted some castings made that are too large for my equipment.
It is owned by a very enthusiastic chap who gave me lots of advice regarding using petrobond sand.
Contrary to lots of you tube advice using engine oil is a complete no . They remix with a very small amount of molasses and have been using the same sand for a long time . The more you muller it the better the surface finish and it improves every time it is reused . J winter foundry supplies sell petrobond snake oil but he thought that molasses was just as good and much cheaper,
 Would certainly recommend him as very happy to do one off castings in cast iron, aluminium brass bronze etc.
  Mike

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8661
  • Country: gb
  • East Sussex, UK
Re: Petrobond moulding sand
« Reply #7 on: March 01, 2022, 09:44:57 AM »
Mike that’s interesting. Did he give you any idea of proportions? And molasses is quite variable in its runnyness
Andrew Mawson
East Sussex

Offline smiffy

  • Full Member
  • ***
  • Posts: 167
  • Country: gb
Re: Petrobond moulding sand
« Reply #8 on: March 01, 2022, 10:23:49 AM »
He did not give any amounts as there are too many variables .  He was mixing about 60 kgs at a time and adding molasses in
very small quantities until he was happy with the feel of the  sand .He also said that it needed mullering for 10 minuets or more before you can tell if it is correct and the sand stands up well to multiple uses before it need more molasses added
  He said that you could also use linseed oil but the used sand needed much more mullering to recondition it  in between uses .
  I will start with about a egg cup full for every 20 kgs of sand  but first I need to make a proper muller   Mike

Offline vtsteam

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 6363
  • Country: us
  • Republic of Vermont
Re: Petrobond moulding sand
« Reply #9 on: March 01, 2022, 10:56:46 AM »
Interesting. Both molasses and linseed oil are traditionally used in making baked sand cores (I haven't seen them used together -- separate recipes). They both burn out during the pour to allow the core to collapse.

Actually it's generally diluted molasses, called "molasses water". I've used molasses water for baked sand cores (mixed with a little wheat paste or flour) for aluminum molding. They burn out black to loose sand.

Baked sand core w/molasses water/wheatpaste before closing up the mold for a tailstock:
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline tom osselton

  • Hero Member
  • *****
  • Posts: 1194
  • Country: ca
Re: Petrobond moulding sand
« Reply #10 on: March 01, 2022, 05:32:58 PM »
I got a flier from Princess Auto ( Canada ) yesterday offering Petrobond for sale.

Offline russ57

  • Sr. Member
  • ****
  • Posts: 269
Re: Petrobond moulding sand
« Reply #11 on: March 09, 2022, 06:54:31 AM »
Molasses is basically sugar and water, right? Sticky when wet, carbonised when heated to molten metal temps.
Maybe sugar water would work?



-russ


Offline John Rudd

  • Hero Member
  • *****
  • Posts: 2485
  • Country: gb
Re: Petrobond moulding sand
« Reply #12 on: March 09, 2022, 07:14:46 AM »
Sort of right….,molasses comes from sugar cane or beet….quality depends on how it is refined/extracted…

When I worked in South Africa, we fermented molasses that arrived to site by rail tanker, that was black and sticky. Producing 98 proof alcohol, ( drink enough will kill you!) the lees went over to a spray drier plant and eventually turned into animal feed stock….virtually no waste…
eccentric millionaire financed by 'er indoors
Location:  Backworth Newcastle

Skype: chippiejnr

Offline vtsteam

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 6363
  • Country: us
  • Republic of Vermont
Re: Petrobond moulding sand
« Reply #13 on: March 09, 2022, 09:16:25 AM »
The syrupy quality helps in packing the sand mix and holds it together before baking-- maybe better than refined sugar -- you'd have to try it to know. Molasses works, and is traditional, and it's needed in very small quantity, so I haven't tried anything else -- my wife is an avid baker.

I may be doing some baked sand cores shortly, btw.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8661
  • Country: gb
  • East Sussex, UK
Re: Petrobond moulding sand
« Reply #14 on: March 09, 2022, 09:49:01 AM »
I've a feeling Molasses is more like what we call Treacle in the UK.

Molasses is widely available in farm supply shops - if your cattle don't like the silage you've made (too dry, too many rushes etc) dose it with molasses and they'll eat the lot and ask for more!
Andrew Mawson
East Sussex


Offline mattinker

  • Hero Member
  • *****
  • Posts: 1313
  • Country: fr
Re: Petrobond moulding sand
« Reply #16 on: March 11, 2022, 09:49:55 AM »
I have 60 kgs of petrobond sand that needs rejuvenating .I have looked on the net for means of doing this and get conflicting advice . Has anyone done this and what method did you use ,or should I bin it and use green sand  Mike

I use petrobond. when I bought it  I also bought a paste that is sold by the manufacturers in Germany. When I use it, I try to separate out the black layer that's next to the casting and put it to one side to be rejuvenated with the "paste". This is hard going without a muller, which is pretty high on my list of things to make

Bentone clay is used in petrobond sand, it is hydrated with oil, unlike green sand which is frequently has bentonite clay as a binder which is hydrated with water. I couldn't find Bentone here in France, which is why I ended up buying ready made petrobond. I have seen smokeless two stroke oil as an oil additive and rubbing alcohol to make it more fluffy!

Cheers, Matthew

Offline PekkaNF

  • Hero Member
  • *****
  • Posts: 2523
  • Country: fi
Re: Petrobond moulding sand
« Reply #17 on: March 11, 2022, 10:19:16 AM »
Here some cat litter bags contain mostly bentonite. Wonder if that would work? Are all bentonite the same?

Offline SwarfnStuff

  • Hero Member
  • *****
  • Posts: 575
  • Country: au
Re: Petrobond moulding sand
« Reply #18 on: March 11, 2022, 06:24:57 PM »
Peka,
I have seen people using kitty litter bentonite on YouTube and it seemed to me their biggest problem with it was grinding then sieving it to powder form. After that no trouble.
Not done any casting although it is another thing on my list of things to try even if only to melt aluminium and cast usable lumps.
Regards,
John B
Converting good metal into swarf sometimes ending up with something useful. ;-)

Offline vtsteam

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 6363
  • Country: us
  • Republic of Vermont
Re: Petrobond moulding sand
« Reply #19 on: March 11, 2022, 08:20:54 PM »
There are two types of bentonite as clay used by foundry men and also potters here, Southern and Western. They have somewhat different properties. Bentonite  is also used in cattle feed and is available from farm supply stores. Also it is used for a pond sealant.

I have heard for years about kitty litter being used for casting on the web and have yet to see a quality casting made with it. I think I once heard that it was actually already kilned, though not sure about that. If it is still raw, rather than grinding it,  people should be able to soak it in water for a week or so in a bucket to make ia slurry, let it settle, pour off the water, and then dry in the sun on a tarp until a usable consistency -- similar to what some potters do with natural clay.

I think Bentonite is wasted on most casting metals other then iron. By that I mean it isn't necessary to produce high quality castings and any good ceramics grade fireclay, like Hawthorn will work perfectly well for that.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline mattinker

  • Hero Member
  • *****
  • Posts: 1313
  • Country: fr
Re: Petrobond moulding sand
« Reply #20 on: March 15, 2022, 07:55:32 AM »
There are two types of bentonite as clay used by foundry men and also potters here, Southern and Western. They have somewhat different properties. Bentonite  is also used in cattle feed and is available from farm supply stores. Also it is used for a pond sealant.
I think Bentonite is wasted on most casting metals other then iron. By that I mean it isn't necessary to produce high quality castings and any good ceramics grade fireclay, like Hawthorn will work perfectly well for that.

Steve,

When I researched making Petrobond, the site I referred to talked about Bentonite and Bentone, Bentonite is apparently readily available the world over, Bentone, which is used for the oil based sand is much harder to find, at least here in Europe, apparently, it's used in cosmetics. I still haven't found a source for it!

Cheers, Matthew

Offline vtsteam

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 6363
  • Country: us
  • Republic of Vermont
Re: Petrobond moulding sand
« Reply #21 on: March 15, 2022, 09:01:55 AM »
Haven't heard of Bentone before, Matthew. I've never used real Petrobond -- too expensive for my tiny hobby budget, both in original cost and for shipping, since it is heavy. Also, the idea of handling and breathing burnt fumes of some secret commercial oil formulation wasn't as appealing as just working with plain water and steam.

But I am curious about it. I've watched at least one video about someone "making petrobond". It turned out that he was using sanded tile grout mixed with motor oil -- 25 lbs of the grout and a quart of the oil. The video didn't inspire me to go out and try it, and it didn't seem convincing that the sand he'd come up with was the equivalent to Petrobond. I guess partly because he seemed so odd in his casting practice anyway. Also, modern sanded grout has some odd organic additives. But again it was of interest. And, who knows, maybe his results were equivalent, and the health effects not pressing. The camera work wasn't good enough to really read the casting finish quality.

My understanding about Petrobond is that casting finish for aluminum is greatly improved by it -- that's its main advantage. Also that it isn't applicable for iron, but I may be wrong in that.

I think little on the internet has been devoted to improving finish for aluminum casting using conventional water/clay based greensand. But actually there is a fair amount you can do. I think using a facing sand is important, as is moisture control, and understanding local ramming pressure to yield a high quality result.

I would like to try Petrobond to see for myself if there is an advantage in finish, compared to what I'm used to and to what degree it's improved.  But as I said, it's not in my tiny budget for shop work.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline mattinker

  • Hero Member
  • *****
  • Posts: 1313
  • Country: fr
Re: Petrobond moulding sand
« Reply #22 on: March 15, 2022, 09:21:38 AM »
Steve,

my understanding was that as there was less expansion with the oil than with steam, finer sand could be used as it didn't need to be as open to the expansion. This is where the Bentone comes in as it sticks the sand together using oil to "wet" it.

Here's a link to a K bond sad recepie.

https://www.homemodelenginemachinist.com/threads/foundry-sand.30505/

Cheers Matthew

Offline vtsteam

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 6363
  • Country: us
  • Republic of Vermont
Re: Petrobond moulding sand
« Reply #23 on: March 15, 2022, 09:22:58 AM »
Matt, here's a retail supplier of a variety of bentone (there seem to be several mfr's and types listed on the net).

https://www.earthpigments.com/bentone-hd/#techdata
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline vtsteam

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 6363
  • Country: us
  • Republic of Vermont
Re: Petrobond moulding sand
« Reply #24 on: March 15, 2022, 09:41:45 AM »
That recipe is interesting Matt. One thing I notice is that it calls for 100 mesh sand for the K-bond. That's not finer than conventional aluminum greensand, and what I've found, personally is that even finer sand can be used in a greensand aluminum mold if it is used as a facing sand, while backing it with more porous sand. My regular greensand is 50 mesh, I believe, but I've used up to 120 as facing.

I'd really like to do side by side castings in Petrobond (or K-bond) and faced greensand, because the only way I can really tell what the advantage is (and whether it is justified in my own use) is to actually try it myself. We all do things a little differently, so I can't judge by the results others publish about it.
I love it when a Plan B comes together!
Steve
https://www.youtube.com/watch?v=4sDubB0-REg

Offline mattinker

  • Hero Member
  • *****
  • Posts: 1313
  • Country: fr
Re: Petrobond moulding sand
« Reply #25 on: March 16, 2022, 06:11:45 AM »
Matt, here's a retail supplier of a variety of bentone (there seem to be several mfr's and types listed on the net).

https://www.earthpigments.com/bentone-hd/#techdata

Thanks Steve,
When I was looking into this, 15 years ago, I was searching in Europe! My Petrobond with additive paste is still going strong

Cheers, Matthew