Regarding mesh sizes when using a rack and cloth press

[Magnus Lindström]

Hi!

Me and and friend of mine have decided to make our own rack and cloth press in order to work more efficiently during the upcoming season.
After having done a lot of research we have a basic blueprint of the press and everything is more or less outlined. However, when I set about to find proper press cloths I found that they're extremely expensive! Brouwland - which is the only website I have found that will ship to Sweden - sells 150 x 150cm of polypropylene for 72.45€.

Although I had not earlier managed to find any press cloths sold from Sweden, I now started calling various net-manufacturers and asked them if they could provide me with a polypropylene (which, to me, seems to be the food-friendly plastic of choice?) net for, perhaps, a more manageable sum than my entire life savings. To my disappointment, I am unable to find a net with the mesh-size of 3mm, but 5mm and up seems alright.

To the question: Very few sites specify the mesh-size of their cloths more than declaring it either coarse or fine. The one I found gave the size of 3mm so that's what I've been asking for. Is it simply ridiculously expensive to buy proper cloths that will handle the press or have I not looked far enough? Is 3mm an appropriate mesh-size? Are there any other plastics that I should consider using?

(i will be using a jack with 1.5 metric tonnes)

This is my first contact with this cider workshop and, as you all can see, I am unexperienced in the field of cider making.
I would be grateful for any input, idea or word of advice! :)

Thanks beforehand/ Magnus

[Onslow's dry]

Hi Magnus,

Had you considered that there is an alternative to pulp and press?

Rich and I favour juice and strain. The entry costs can be low and the efficiency, typically 65% by weight juice recovery, is good. Moreover, using a high performance juicer, I can recover apple juice at the rate of a gallon (4.5 litres) in four minutes.

Please have a look at our YouTube video and see what you think : http://youtu.be/Qvc0cCh5r0c.

If you want to read more there is my blog which contains much of our story: http://juiceandstrain.wordpress.com/

regards,

Nevin

[Ray Blockley]

Hi Magnus,

 

Many small-scale makers of cider using home-made pack or rack-and-cloth presses have had very good results using net curtaining that is often found hanging in the windows of British homes. I have seen such curtains in France and Spain - do you have them in Sweden?

 

A good large shop which specialises in curtains or fabrics in general should have a range of net curtaining material that will suit. Go for mesh size (as you state) but above all strength.

 

I used 'Terylene' (or correctly PET: Polyethylene terephthalate) net curtain material of 2mm mesh size. PET is very food safe (most plastic drink bottles are made of PET), the curtains are easily washable, and if you select wisely they are *very* strong. You can also get the curtains with a very pretty pattern if you wish but it doesn't add to the flavour of the cider!

 

Check the width, buy by the metre and cut to size. Any household sewing machine (with appropriate thread) can be used to hem the material.

 

My press used a 6 Tonne hydraulic jack (later 10 tonne) and the nets did not burst in the 10 or so years that we used them.

 

Cheers, Ray

 

--------

Ray B

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[Andrew Lea]

On 17/07/2013 17:06, Magnus Lindstr�m wrote:
>
> Is 3mm an appropriate
> mesh-size? Are there any other plastics that I should consider
> using?

I have some 'official' Voran cloths made from woven polyester which have
a mesh size of appx 1 mm * 2 mm. I think even 3*3 mm might be a bit on
the large size and 5*5 mm would certainly be too large in my opinion.

Like Ray I also used terylene curtain net cloths for many years (I did
replace them once but they were very cheap).

Have you considered horticultural butterfly netting such as Enviromesh
which you can buy by the metre? See
http://www.enviromesh.co.uk/enviromesh-10-c.asp This is made from
polythene and has a mesh size of 1.35 mm (quoted). It is now widely
available (at least in the UK).

Andrew

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Wittenham Hill Cider Portal
www.cider.org.uk

[magnus.lindstrom91]

Hello there

Thanks for your input. After talking to my buddy we decided to use cotton muslin which is apparently widespread. It wasn't that expensive and if it happens to break/prove unuseful maybe we'll change to the types used commercially (or curtains, which we do have in Sweden :)).

Thanks again /Magnus

[Andrew Lea]

On 17/07/2013 20:24, magnus.lindstrom91 wrote:
> Hello there
>
> Thanks for your input. After talking to my buddy we decided to use
> cotton muslin which is apparently widespread.

That is very traditional! You should though be aware that it absorbs a
lot of water / juice so it is much more difficult to clean and dry off
than the synthetic polymers (so a spin dryer is a great help!). It
should do the job though.

[Andrew Lea]

On 17/07/2013 20:24, magnus.lindstrom91 wrote:
>

> After talking to my buddy we decided to use
> cotton muslin which is apparently widespread.

Oh and you should probably boil the muslin in water first to remove any
'sizing' or stiffener (like starch) that may have been added during
weaving. That is the traditional recommendation when using new cotton
press cloths anyway.

[richard marlborough]

hi

did you click on the juice & strain link? if so, what did you think? if you had the best quality cider apples, why would you not use this method for anything under 1000kg per year? you will get a juice yield of at least 60%

any thoughts would be most appreciated

cheers

rich

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[Magnus Lindström]

Hi Rich

Yes, I did click the link but it is not something we are considering I'm afraid. It will simply be more fun to use an old-fashioned rack and cloth press. And since we're doing this mostly for the fun of it (and secondly for the cider) this is how it will be.

Best regards, Magnus

[richard marlborough]

hi magnus,

many thanks for the feedback. a rack & cloth press is fun but i would avoid any kind of basket press or manual scratter.

best regards

rich

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[Thomas Barnes]

On Wednesday, July 17, 2013 3:37:29 PM UTC-4, Andrew Lea wrote:

On 17/07/2013 20:24, magnus.lindstrom91 wrote:
> Hello there
>
> Thanks for your input. After talking to my buddy we decided to use
> cotton muslin which is apparently widespread.

That is very traditional! You should though be aware that it absorbs a
lot of water / juice so it is much more difficult to clean and dry off
than the synthetic polymers (so a spin dryer is a great help!). It
should do the job though.

You've already made your decision, but I will mention that burlap, like that used to make old-fashioned grain bags, also works. That was a traditional material. It's tough, it's easy to clean, doesn't absorb that much juice and is easy to handle when you're wearing gloves. That's what the press that I've helped to run uses. Use the finest mesh burlap you can get, or use multiple layers sewn together. Polypropylene mesh, like that used for modern malt bags, might also work but I'm not sure if its considered food safe for contact with apple juice.

Regardless of material, after pressing, you shake the remaining pulp out, hose them down (outdoors, it's messy work) and then run them through a conventional clothes washer (no detergent, cold water) to get the remaining juice and pulp out. Then, air dry them to make sure they don't pick up any fungus.

[Martin@Briz]

On Wednesday, 17 July 2013 20:37:29 UTC+1, Andrew Lea wrote:

On 17/07/2013 20:24, magnus.lindstrom91 wrote:
> Hello there
>
> Thanks for your input. After talking to my buddy we decided to use
> cotton muslin which is apparently widespread.

Hello Magnus,

 

Muslin rots very quickly. You won't get many years' of use out of it. Nylon is the way to go. Net curtains are good, as has been suggested, but I am currently using close-weave garden netting. The current lot that I'm using has been in use under a 4-tonne jack for 3 years and is in perfect contion still. It'll probably last longer than I will!

 

Cheers,

 

Martin

[Peter Eveleigh]

On Wednesday, 17 July 2013 17:06:16 UTC+1, Magnus Lindström wrote:

Hi!
  Hi Magnus,

To add to your query on mesh size, i use a polyester mesh approx 2 mm grid, purchased from Weymouth (UK).  I don't know if he exports but you can send an email to  in...@englishseadog.com. He offers a large variety of synthetic mesh and quite often advertises on ebay if you search for cider making mesh.

(i will be using a jack with 1.5 metric tonnes)

How much thought have you given to the pressures that are involved here? A 1.5 MT jack is hardly going to tickle the edge of you apple pulp unless it is in a press of about 200 x 200 mm.  The experts will tell you that you require approx 100 psi (7.03 KG force / cm square) to extract a respectable yield of 60%. When designing my presses, my background research showed what sort of pressures (tons force) were required - when spread over the surface area of your cheese, to get a satisfactory yield. I have attached a file of these results so you can  get a feel for what size of Jack you need, given the size (surface area) of your press. - Apologies that they are in Imperial units, showing my age!
Hope this helps
Peter

[Magnus Lindström]

Hi everyone and thanks for all of your advices!

To Peter:

I have not given the pressures involved any thought at all. Our only requirements of the jack was the height difference between the lowest and highest settings. I guess we just figured that 1.5 tonnes of pressure sounds like a lot which would make it enough.

Looking at your .pdf, I'm afraid that am having some difficulties deciphering the meaning of most of the numbers, so maybe I'll just give you the dimensions and you can help a fella out? :)

The pieces of cloth we're buying are 130x130cm and I figured that an overlap of 10cm (from each side, so to speak) will be sufficient. So when I fold the cloth with 10cm overlap it will yield a bag with an area of 110cmx110cm = 12 100cm^2 = 1875.5in^2. Since we plan on using 4 bags the total area should be 1875.5 x 4 = 7 502in^2.

An early estimation of mine was to make the sides 7cm or 2.8in high which would leave the sides of this cuboid 48cm or 18.9in long (after removing the earlier mentioned overlap). 

Cuboid dimensions: 18.9 x 18.9 x 2.8in.

This is where I'd like some help, since I can't wrap my head around your stats... Would be much appreciated. What jack would be suitable for my setup? Is there something fundamentally wrong with the dimensions of my cheeses?

Thanks beforehand, Magnus

[Magnus Lindström]

Hi again

Let me save someone the trouble of explaining physics over the internet to a dummy. I see what you mean now, and the numbers in your sheet as well.

Having read up on psi vs juice yield I think we'll shoot for about 70psi instead of the 100 you mentioned, Peter, since it's our first press and my second summer of cider making so I'm not expecting too much:)

Thanks again, Magnus

[Claude Jolicoeur]

Magnus,
70 psi is perfectly acceptable for a hobbyist press. The difference in yield won't be that much compared to 100 psi, and you can leave your cheese under the press for longer to improve the yield.

However, if your jack is only 1.5 ton, to obtain 70 psi would mean your racks shouldn't exceed 6.5 inches wide or 16.5 cm... very small! The capacity of such a small press would be about 3 kg of apples per load.

I don't think it is worth the trouble to build anything that would be under 4 tons of load. This would suit a press with 16 inches free width between uprights (41 cm) and racks 12.75 in wide (33cm). Such a press would have a capacity of close to 20 kg of apples per load.

Claude

[Magnus Lindström]

Claude

I forgot to mention that we're moving up from 1.5tonnes to 10tonnes to be able to use an area of about 45cm when reaching 70psi.

Sorry, but thanks for the concern:)

/Magnus

[Claude Jolicoeur]

OK - that's perfect sizing, 45cm racks with 10 tons. With 5 to 6 racks you can then have a press with over 50 kg of apples per load. Free width between frame uprights should be about 55 cm.
Claude

[Peter Eveleigh]

On Friday, 19 July 2013 18:33:09 UTC+1, Magnus Lindström wrote:

Hi again

Hi Magnus,

Well done for unscrambling the PDF data; you only needed the  left side - "target force required" as the remainder (right side) relates to using a trapezoid screw - as opposed to the Jack, providing data on the effect of different T handle lengths (as the force applied) via friction losses through to the pressure (psi) applied to the fruit. I used this data for calculating the size - to - strength ratios of the oak construction - particularly with regard to the top rail and how it should be fixed (jointed) to the side rails. I have used the 100psi target not only as a useful design pressure, it also caters somewhat for the stronger folk who might want to "strangle " the fruit whilst pressing - Don't offer a handle which is too long!

In the meantime Claude's posts have squared the circle and, as a "non cider maker" , I would certainly not argue!

In closing - for the making of your press:- don't forget the 50 odd mm gap between the side of the racks & side rails. And also, when you make your former:-"An early estimation of mine was to make the sides 7cm or 2.8in high which would leave the sides of this cuboid 48cm or 18.9in long" - make sure that the inside dimension of the former is a good 50 mm less than the outside dimension of the slat (cheese base) in order to allow the cheese to "flatten out" and remain under pressure during pressing whilst still allowing the juice to flow better down the outside edges into the collection tray.

Please get in touch if you need any further help & good luck
Peter