Hi folks,

I bought the book “200 easy homemade cheese recipes” from Debra Amrein-Boyes. Seems (as far as I read until now) a marvellous book, thanks to down445 and Tammy for your recommendations.
But I’ve got a question about what’s told there about pressing:

Shortly stated is light pressing 5-10 psi, medium 10-20 psi and firm 20-45 psi.
I know that psi is pounds per square inch, only I don’t count 1 kg to be 2 pounds, according to me a pound = 0.45 kg, but that is not the real issue.

When I have a Kadova mould for a 1 kg baby Gouda, the diameter of the follower is 14.5 cm. This is 14.5 / 2.54 = 5.7 inch. So the radius will be 2.85 inch.
Formula for the surface of a square is pi x R2, so this is 3.14159 x (2.85 x 2.85) = 25.5 square inch.
The light pressing would be 5-10 psi, so let’s take 5 pound x 25.5 square inch = 127.5 x 0.45 = 57.4 KG !!! And about 500 kg (45 x 25.5 x 0.45) for Cheddar ??
I seem to be a factor 10 to high. What am I doing wrong here in this calculation??

yup western KG is 2.2lb
Do the calculations in all metric, or all in standard.
————————————————————————————————————-
Surface Area of a Cube = 6 a 2

(a is the length of the side of each edge of the cube)

In words, the surface area of a cube is the area of the six squares that cover it. The area of one of them is a*a, or a 2 . Since these are all the same, you can multiply one of them by six, so the surface area of a cube is 6 times one of the sides squared.
————————————————————————————————————-
Surface Area of a Cylinder = 2 pi r 2 + 2 pi r h

(h is the height of the cylinder, r is the radius of the top)

Surface Area = Areas of top and bottom +Area of the side

Surface Area = 2(Area of top) + (perimeter of top)* height

Surface Area = 2(pi r 2) + (2 pi r)* h

In words, the easiest way is to think of a can. The surface area is the areas of all the parts needed to cover the can. That’s the top, the bottom, and the paper label that wraps around the middle.

You can find the area of the top (or the bottom). That’s the formula for area of a circle (pi r2). Since there is both a top and a bottom, that gets multiplied by two.

The side is like the label of the can. If you peel it off and lay it flat it will be a rectangle. The area of a rectangle is the product of the two sides. One side is the height of the can, the other side is the perimeter of the circle, since the label wraps once around the can. So the area of the rectangle is (2 pi r)* h.

Add those two parts together and you have the formula for the surface area of a cylinder.

Surface Area = 2(pi r 2) + (2 pi r)* h

Herman,

Your calculations are correct.  It is the surface area that you want to consider.  However, I don’t think that whoever came up with those light, medium, and firm pressures was in fact considering PSI.  He was likely talking about actual weight.  Those weights would be about right for a 4” mold.  Personally, I press my cheddar at about 4 PSI - which for my 6” mold comes to about 110 lbs.  This is quite adequate.  If I followed the guidelines you have read it would be 1,410 lbs, which is obviously not correct.

OK Neil, I understand that this is the way to calculate the total surface of a cylinder. But what do I have to do after I calculated the surface? This means that I have an even bigger surface in square inches , so I need even more weight? That can’t be right! I recall that Tammy mentioned calculating the pressure weight some time ago, Tammy can you explain this? I understood that you have also have the book of Debra Amrein-Boyes…

Some people put a bathroom scale under the cheese and set the scale like that.

Try this;

http://www.rickandlynne.com/rick/go/forums/viewthread/710/

http://cheeseforum.org/forum/index.php/topic,7096.0.html

Thanks Neil, I have read both threads and other topics about this on cheeseforum, but I’m still not sure about how to calculate this. So I dropped Debra Amrein-Boyes a mail.
She has a nice website on http://www.farmhousecheeses.com and it was funny to read that she started to write the book during a stay on the Greek island Paros, where I have been in the 80’s and 90’s over a dozen times during summer holidays…

I received an answer from Debra Amrein-Boyes yesterday. The psi’s in her book are indeed meant for a hydraulic press. On cheeseforum.org I found a small program and a sheet for calculating pressure. I will have a look at that later and I will let you know.

I took those hydraulic press numbers and put a decimal point in them, and it seems to work. I have compared the pressing weights for every cheese I make with every recipe I can find and it usually works out. If it says 20 in the hydraulic press chart, I use 2.0 psi. It’s the same thing with the Peter Dixon website pressing instructions. I never use just the one book instructions.

Thanks you Tammy, it indeed seemed 10 times too high. Unfortunately Debra did not give any other instructions to calculate it. I didn’t have time yet to look into the sheet and program I downloaded, but will do that one of these days. Until now I mostly did a rough guess and didn’t have failures due too bad pressing…

I thingk each system is different. I liked the system someone used in using a scale to see what the pressure is and then marking their press with the weights so its no guessing.

Yes, you can use a scale or you can calculate the pressure, but there is a difference between putting e.g. 10 lbs on a mould with a diameter of 5 inch or 10 lbs on a mould with 20 inch, that’s were you should calculate with psi IMO…

I agree with both of you.  The diameters determine the weight; but it’s also good to know how much weight your particular press requires for each PSI level.  BTW, I’d loooove to see a 20” diameter cheese!  But can you imagine the pressure required?

Well, imagine an original Emmentaler! That’s up to 130 KG or 286.6 lbs with a diameter up to 100cm or over 39 inch…
Unbelievable size, how long will it last to consume that with a family of four

For me, quickly LOL, love the stuff.