Sand
To build a model pyramid out of plaster of Paris, coat the inside of an ice cube tray with petroleum jelly. Pour plaster of Paris inside and allow to dry. Once dry, place the blocks in a square pattern, gluing them together with plaster of Paris. Stack another row atop the bottom row, insetting each row to form a pyramid shape.
To plaster over foil covered board, you will first need to apply a bonding agent to the foil surface to help the plaster adhere. Then, apply a base coat of plaster over the foil, making sure to smooth it out evenly. Finally, add a finish coat of plaster once the base coat has dried to achieve the desired texture or finish.
The purpose of the plaster scratch coat is to provide a rough surface for the next coat of plaster to adhere to, ensuring better adhesion and a stronger bond between the plaster and the surface being covered.
The purpose of applying a scratch coat plaster in the process of plastering a wall is to create a rough surface that helps the next layer of plaster adhere better. This base coat also helps to level out any imperfections in the wall and provides a strong foundation for the final finish coat of plaster.
Buy some concrete or plaster of paris. Mix and pour in a small square baking pan (one you don't use for baking is best). Coat the mold with cooking spray or vaseline and when the plaster starts to set up, press the paw into it-you could probably even do stepping stones with the right mold.
Traditional plaster is made of hydrated lime, sand, water, and horse hair (or some other type of hair) added for tensile strength. When mixed, traditional plaster has the consistency of runny peanut butter. As plaster sets, the lime within the plaster mix absorbs Carbon Dioxide and is essentially converted back into limestone, resulting in a hard and durable material. Plaster is usually applied in three coats: the scratch coat, brown coat, and finish coat, and is rather labor intensive.
The finish plaster is normally white all the way through. It sounds like you are dealing with a pool that has been replastered by the method of putting a "brown coat"/"scratch coat" (the gray plaster you noted) over the original finish plaster surface, and a new finish coat of white plaster on top of that. The scratch coat more like a thin concrete than plaster (doesn't have the white marble dust in it) and is used to get a better bond to the old surface.
plaster with neat coat of cement
To apply a plaster skim coat for a smooth finish on walls or ceilings, first, prepare the surface by cleaning and priming it. Then, mix the plaster according to instructions and apply it evenly using a trowel. Smooth out any imperfections and let it dry completely. Sand the surface lightly, apply a second coat if needed, and finish with a final sanding for a flawless result.
In olden days of yore plaster was applied over wooen lath which gave the plaster something to adhere to . Thus a much heavier coat of plaster could be applied because of the space between the lathes. the next day a second coat was applied called the skim coat because it's only purpose was to fill in the imperfections left from the first coat. fast forward to now the plaster comes in sheets much the same as sheetrock ex cept it is blue, and rightly called blueboard , after the hangers screw the bluboard to the wall and ceiling a team of plastererscome in and put a skim coat of plaster over the whol board, the joints require a heavier coat. After this coat dries in a couple of hoursor less the plasterers come back and apply a veneer thickness to the wall and dampen the plaster with a brush being waved in front of the board.Thus completing the plaster job. Now a oldtime plasterer like my brother-in-laws brother is a real plasterer and I was lucky enough to have him plaster my house when we built it, would walk off a job if they wanted him to use blueboard., as he is a old time plasterer who is an artist as he makes crown mouldings an other plaster designs on top of a coulple of inches thick.of base plaster. if you get a chance to see a real plaster job and a blueboard job you can tell the difference and both shine over sheetrock and compound job.
They are the same thing. A skim means just a thin finishing coat of plaster about 3mm or so thick, just enough to cover any minor imperferctions on the wall.
I use basic drywall primer over all of those.