Author Topic: A few words about Petrobond  (Read 3056 times)

PatJ

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A few words about Petrobond
« on: November 27, 2013, 04:43:16 PM »
I am new here, so I don't know if this is duplicate information or not, but for what it is worth:

Petrobond (oil based foundry sand) comes in two varieties; one uses oil and one uses oil and a catalyst.

Petrobond tends to dry out and lose its "green sand" strength, which is sort of a measure of how well it holds a shape in the mold.

If you are using petrobond that is the catalyst variety, you can try adding a little catalyst first, and it is said that catalyst generally will restore the sand without any further effort.

If the catalyst does not bring you back to green strength, then a little oil can be added, but not too much oil or you will lose green strength.

Many people use a muller or mixer of some type to fluff up their petrobond.
I have used the wife's heavy duty kitchen mixer (shhhh.......don't tell her about that, she would not understand).

Some people mull sand by putting in on plastic on the ground, and rolling it around and stepping on it.

A muller works best.

Petrobond gives a very good surface finish, and since it is oil-based, it does not have gassing problems that may be present with water-based sands (water based sands can create steam, which can cause problems).

Sorry if all this has been previously covered somewhere here.


Offline smithdoor

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Re: A few words about Petrobond
« Reply #1 on: May 17, 2015, 12:23:42 AM »
I have use petrobond
A alternative for  catalyst is alcohol works great

Dave

Offline ART

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Re: A few words about Petrobond
« Reply #2 on: May 17, 2015, 12:45:56 AM »
I have a small homeshop foundry, and have used and reused the same catalyst type petrobond for about 10 years. I use a fuel additive called Heat for my alcohol source, and smokeless 2 stroke motor oil for the oil. I have found that it does not take much of either to bring back the green bond strength. I spray paint all of my patterns with enamel, and found that if I use too much Heat/alcohol the paint begins to dissolve having the petrobond stick to the patterns when ramming up the molds. This happens with shellac coatings also. I have never mulled the petrobond after use because I do not have a muller. Just add a little oil and Heat, riddle, and place in a covered plastic bucket until the next use.
                                                                                                                                  Art

Offline smithdoor

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Re: A few words about Petrobond
« Reply #3 on: May 17, 2015, 12:53:58 AM »
Use car or truck and your driveway as a Muller
I have build a 50 lb Muller but have had move and let go with foundry

Dave
 
I have a small homeshop foundry, and have used and reused the same catalyst type petrobond for about 10 years. I use a fuel additive called Heat for my alcohol source, and smokeless 2 stroke motor oil for the oil. I have found that it does not take much of either to bring back the green bond strength. I spray paint all of my patterns with enamel, and found that if I use too much Heat/alcohol the paint begins to dissolve having the petrobond stick to the patterns when ramming up the molds. This happens with shellac coatings also. I have never mulled the petrobond after use because I do not have a muller. Just add a little oil and Heat, riddle, and place in a covered plastic bucket until the next use.
                                                                                                                                  Art