How can I dissolve dried plaster of paris?

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In summary, the conversation discussed a group's experience using plaster of paris for a scale model and encountering difficulty in removing it from a glass casserole. The solution to dissolve plaster of paris was suggested to be using water and time, or using acid or sugar to accelerate the process. Another method mentioned was converting the dihydrate back to the hemihydrate by baking it at 150F for several hours. A microwave heating technique was also mentioned as a possible solution.
  • #1
ninapilapil
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My groupmates and I were using plaster of paris for our Arch 10 scale model of a chair. We used a glass casserole for the first trial. Kind of stupid. We covered it with oil before putting in the mixture but when the mixture dried, we couldn't get it out anymore. How can I dissolve plaster of paris?
 
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Water and time will eventually get it out. Acid or sugar will accelerate it somewhat.

You can convert the dihydrate back to the hemihydrate by baking it at 150F for several, perhaps many, hours. It should then crumble easily.
 
  • #3
chemisttree said:
Water and time will eventually get it out. Acid or sugar will accelerate it somewhat.

You can convert the dihydrate back to the hemihydrate by baking it at 150F for several, perhaps many, hours. It should then crumble easily.

An estimate of how long?
 
  • #4
ninapilapil said:
An estimate of how long?

For the heating step? It should take from 2-4 hours but depending on the maximum cross section the water must traverse on the way out, that could increase significantly... perhaps as much as a day or more.

http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1432.pdf" [Broken]

http://cr4.globalspec.com/thread/25981/Gypsum-dehydration" [Broken]

I like the idea of microwave heating. Heat slow at first and then ramp up the power.
 
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There are a few different methods you can use to dissolve plaster of paris. One option is to use warm water and a scrub brush to gently scrub away the dried mixture. You can also try using a vinegar solution, as the acid in vinegar can help break down the plaster. Another option is to use a commercial plaster remover, which can be found at hardware or home improvement stores. Just be sure to carefully follow the instructions on the product.

In the future, it may be helpful to first line your casserole dish with a layer of plastic wrap before pouring in the plaster mixture. This will make it easier to remove the dried plaster once it has set. Additionally, you may want to try using a non-stick cooking spray instead of oil to help prevent the plaster from sticking to the dish.

Overall, it's important to carefully plan and prepare before using plaster of paris to avoid any difficulties with removal. I hope this helps and good luck with your scale model project!
 

What is "Dissolve Plaster of Paris"?

"Dissolve Plaster of Paris" is a fine powder form of gypsum that is mixed with water to create a paste used for many different purposes, such as molding, casting, and repairing objects.

How do I dissolve Plaster of Paris?

To dissolve Plaster of Paris, mix it with water in a clean container. The ratio of water to Plaster of Paris is typically 3:1, but can vary depending on the desired consistency. Mix the two together until the mixture is smooth and free of lumps.

What is the purpose of dissolving Plaster of Paris?

The purpose of dissolving Plaster of Paris is to create a workable paste that can be used for various tasks, such as creating molds, filling cracks, and making sculptures. The dissolved mixture can also be used to create a smooth surface on walls, ceilings, and other surfaces.

How long does it take for Plaster of Paris to dissolve?

The time it takes for Plaster of Paris to dissolve depends on the amount of water used and the temperature of the water. In general, it can take anywhere from 5-10 minutes for the mixture to fully dissolve. It is important to mix the mixture well and use it within 10-15 minutes before it begins to harden.

What are some safety precautions when working with dissolved Plaster of Paris?

When working with dissolved Plaster of Paris, it is important to wear protective gear, such as gloves and a mask, to avoid inhaling or coming into contact with the mixture. It is also important to properly dispose of any leftover mixture and not pour it down the drain, as it can harden and cause clogs.

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