Casting sand

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Lazz
Posts: 155
Joined: Sun Jul 29, 2012 11:06 pm
Location: The Warm Arizona Deserts... Phoenix to be precise...

Casting sand

Post by Lazz » Wed Feb 24, 2021 5:50 pm

The petrobond I use to cast has lost its strength.
After a lengthy discussion with Lancaster Foundry. A phone call to Lancaster foundry is answered by a nice lady and when my questions got long she transferred me to the owner who was more than just helpful. In order to restore my petrobond I would have to buy binder and catalyst. Unfortunately Lancaster Foundry doesnt offer products in hobby sizes. I could use 200 or so pounds of casting sand... not tons... The estimate to make roughly a ton is only $450 to $500 which pretty much made me wonder if my life would be long enough to wear out another 200 pounds of sand.

Buying more petrobond from the person I originally bought from isnt going to happen. The only response you get from that place is when you send money. Hard questions go unanswered, Questions like, is this Petrobond I or Petrobond II, do you have binder or catalyst I can buy to refresh the stuff I bought from you? So Im voting with my wallet there. Being from Arizona this might be the only vote that counts anymore.

Greensand is a possibility to be looked into. While waiting for 120 mesh Silica sand to become avabile I checked out play sand and kitty litter. Lets just say If you are trying to save money with this path you need a new hobby. Play sand sifted with a 1/8" screen will remove nearly 1/3 of a 50 pound band. When a 50 pound of play sand costs about $6 then $18 will make nearly 100 pounds of sand. This sand is coarse to say the least. The effort to sift this sand is an afternoon of effort. When a 100 pound bag of 120 mesh is only $20. A 100 pounds of coarse play sand for only a $2 saving seems like false economy.

Running kitty litter thru a muller is a dusty, messy event. 3 pounds of kitty litter did not add to the greensand strength of 20 pounds of sand. 5 more or even 10 more didnt help much either.
As the sand dried out in the Arizona heat would it crust over or harden? Needing to be mulled before every casting.

Kbond is the next option. To make K-bond I would need Organo Bentone 34

To make usable greensand I need a better binder than kitty litter.

Does anyone have any suggestions where to find Petrobond binder or catalyst or maybe a binder for greensand?

jscarmozza
Posts: 480
Joined: Mon Mar 03, 2014 5:09 pm

Re: Casting sand

Post by jscarmozza » Wed Feb 24, 2021 6:17 pm

Lazz, some play sand, especially the white stuff sold at the big box stores, is limestone. No good for green sand casting. A good source for bentonite is your local well driller. You'll have to research this because it was hear say to me, but I heard that PetroBond could be rejuvenated with 2 cycle motor oil. I don't know if that's true so check it out if you're inclined to do it.
John

Lazz
Posts: 155
Joined: Sun Jul 29, 2012 11:06 pm
Location: The Warm Arizona Deserts... Phoenix to be precise...

Re: Casting sand

Post by Lazz » Wed Feb 24, 2021 8:42 pm

jscarmozza wrote:
Wed Feb 24, 2021 6:17 pm
Lazz, some play sand, especially the white stuff sold at the big box stores, is limestone. No good for green sand casting. A good source for bentonite is your local well driller. You'll have to research this because it was hear say to me, but I heard that PetroBond could be rejuvenated with 2 cycle motor oil. I don't know if that's true so check it out if you're inclined to do it.
John

Here in Arizona limestone isnt a common thing. I bought 3 bags from different places to check the quality of different brands. The play sand I have does not appear to be crushed rock. All 3 bags look and feel just like California beach sand.

I too have seen several petrobond rejuvenating recipes. I have tried the both non detergent 30w motor oil and synthetic 2 cycle oil with alcohol method. It didnt do much more than make an oily messy sand. As well I discussed it with the gentleman at Lancaster Foundry. In their opinion the binder in my sand has been burnt out.

FKreider
Posts: 251
Joined: Fri Feb 02, 2018 8:44 pm
Location: Sturbridge, MA

Re: Casting sand

Post by FKreider » Wed Feb 24, 2021 9:08 pm

I bought 50lb of Pretrobond off Amazon - its not exactly cheap at $100 but was free shipping. Was a lot faster and easier than trying to source anything locally or make greensand myself. (sounds like you are experiencing the same problems I encountered when trying to source foundry stand - its a royal pain for the hobbyist to get ahold of.)

Here is the link if you want to go this route:

https://www.amazon.com/gp/product/B07N2 ... UTF8&psc=1
-Frank K.

steamingon
Posts: 54
Joined: Sun May 08, 2005 8:02 pm

Re: Casting sand

Post by steamingon » Fri Feb 26, 2021 11:38 am


Lazz
Posts: 155
Joined: Sun Jul 29, 2012 11:06 pm
Location: The Warm Arizona Deserts... Phoenix to be precise...

Re: Casting sand

Post by Lazz » Wed Mar 24, 2021 8:55 pm

Thank you for the suggestions gentlemen.
The majority of my 200 pounds came from https://petrobondforsale.com/
Unfortunately that gentleman will not respond to questions unless there is money involved.
In a different place I found Petrobond II binder powder and oil in small quantities.
It is sitting on the end of my work bench waiting for me to find time to get to it.

Now and then life kinda interrupts... A good example is the recent zombie apocalypse. When things calm down I will definitely share my findings.

Lazz
Posts: 155
Joined: Sun Jul 29, 2012 11:06 pm
Location: The Warm Arizona Deserts... Phoenix to be precise...

Re: Casting sand

Post by Lazz » Sun May 02, 2021 1:12 am

Today I found time to work on some castings.
Pictures https://imgur.com/a/t26byF1


First I refreshed my petro bond and did couple brass castings . I also tried casting brass in the play sand green sand.

After trying and failing to make green sand with play sand and kitty litter I bought some bentonite for a reasonable price. https://www.ebay.com/itm/bentonite-clay ... Sww41gAhBk

Adding 10 % bentonite to the play sand made for a great green strength. As you can see in the picture the play sand was too coarse to make usable castings. On top of the muller and to the right you can see the green sand failure. Removing the pattern from the green sand it was apparent the finish would be poor. I was considering buying some 120 grit silica sand. The problem I have with green sand is it dries out quickly in the Arizona weather. I did this the first of May on a humid day and the greensand was in hard to break clumps after the pour. I cant imagine what a couple hundred pounds of green sand would be like after an Arizona summer. Petro bond does not seem to dry out.


Adding 2 ounces by weight of each binder, oil and alcohol to 12 pounds of my used sand made a very usable casting medium. It wasnt new petrobond. It did do a great job as can be seen in the picture. Petro bond can make brass look good right out of the casting. Using 2 oz of alcohol per 12.5 pounds of sand may have been over kill.

The petro bond powder and oil can be found here.
https://www.ebay.com/itm/Professional-P ... SwzdZgHcP0
After contacting the seller about petro bond oil, for a small increase in the total price the seller included 16 oz of oil.

For me about $55 fixed just under 100 pounds of old petro bond.
I got nearly a perfect forward reverse lever with the petro bond and an unrecognisable lump with the play sand green sand.

FYI brass shrinks more than aluminum.

Harold_V
Posts: 18873
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Casting sand

Post by Harold_V » Sun May 02, 2021 5:37 am

I recently purchased a ton each of Green Diamond sand, one ton of AFS 100 and one ton of AFS115. I'm using it as green sand, but have yet to pour, due to issues with my induction furnace cooling system. I am totally pleased with the way it handles, and have concluded that, for me, the best way to deal with it is to store it dry and add water (and mulling) as it is needed. I have mixed and mulled three hundred pounds at this point, enough to prepare four flasks for pouring. When it is not in use, it is stored in 5 gallon buckets.

I have no real foundry experience at this point, but it's pretty clear to me that for iron, oil tempered sand is not acceptable. For that reason, none of this may be of interest to you, nor does it apply to you.

The cost of western and southern bentonite, prepared for foundry use, is not expensive if you make your purchase from a foundry supply house, as I did. The sand was not very expensive, either. Less than $14.00/100 pounds. No screening, no discarding and very little dusting. I have enough sand to fulfill my potential needs indefinitely.

For iron, I am using only 6% bentonite, equal parts of western and southern, each of which provide desirable qualities. Water content should be no greater than about 3.5% of the sand mix weight. By allowing my sand to dry between uses, it's easy to keep a proper balance. Even here in damp Washington, it dries in a day or so. Not suggesting that's what you should be doing--and I may discover it's not a good idea for me, either--but for occasional casting it seems to be the logical approach for using green sand.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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