Grey insulating cardboard - UK Vintage Radio Repair and Restoration Discussion Forum

Uncle Bulgaria · 29th Aug 2019, 9:54 pm

Ahoy,

In my Uhers there are rather fine pieces of thin, stiff, grey cardboard used between circuit boards and covers. Perhaps they aren't anything special, but they have nice pressed, smooth, shiny surfaces.

If I wanted to use anything similiar in my own projects, or replace something in an old piece of equipment, does anyone know the name of this cardboard equivalent, or if it's something one can still buy today? Does it have ratings or did they just use bits of cereal packet?

MotorBikeLes · 29th Aug 2019, 10:12 pm

I dismantled so old battery drill batteries for cell renewal. They had similar card under and around the cells. I replaced it with card cut from a "hanger" out of a filing cabinet. The sort which slide in and out with the files sitting in the "cradle".
try that.
Les.

ajgriff · 29th Aug 2019, 10:30 pm

Is this a corrugated plastic material? If so, the brand name is Correx and sheets are widely available in different sizes. Probably something different.

Alan

Argus25 · 29th Aug 2019, 11:07 pm

This is the card I always use for those applications & more:

https://www.jaycar.com.au/pressboard...erial/p/HG9985

It is around 1mm thick and for cardboard it has an amazing dielectric strength. It also looks very good varnished.Have a look at the battery case made out of it on page 12-13 of this article:

http://worldphaco.com/uploads/USING_...CILLOSCOPE.pdf

PS: the original card Jaycar supplied was a redish color, like that in the article, of late it has changed to a pale brownish color but it is electrically identical.

kevinaston1 · 29th Aug 2019, 11:49 pm

The thin grey cardboard is called FISH PAPER.

It is used on a lot of stereo high power amplifiers, where the two amplifier channel boards have to be insulated from the metal cabinet.

If you have a local Pro Audio power amp repair company, they may well have some.

I had 20 sheets in stock in my department, before I was made redundant. I doubt it is still there, the new management who took over sent many thousands of pounds worth of parts to the tip.

Kevin

Herald1360 · 30th Aug 2019, 1:03 am

Sounds like what I knew as "Elephantide"- a stiff grey-blue card like sheet material.

Try this: RS Stock No. 775-7790

Terry_VK5TM · 30th Aug 2019, 1:16 am

Yes, "Elephantide"

The use of ordinary cardboard is fraught with danger.

In damp/humid climes, it can absorb moisture and not only become conductive but it also promotes corrosion when in contact with metallic surfaces.

If you really, absolutely, must use cardboard, soak it in varnish or shellac and let it dry thoroughly before use.

Uncle Bulgaria · 30th Aug 2019, 7:41 am

Once again, the hive mind comes up trumps! Looking at listings for 'fish paper' and the RS link, I think we've found it.

As so often with the Infobahn the crucial thing is discovering the right search terms. I'll get some of this and compare it what I have. It's certainly more like cardboard than plasticard.

Thanks all - don't worry Terry_VK5TM, I don't think I'll be desperate to put any projects in cardboard boxes! Shellac, however, is a lovely material with many uses...

Radio Wrangler · 30th Aug 2019, 8:03 am

Transformer winding firms are likely to stock fish paper in some of the thinner grades.

I've always wondered just what fish have to do with it.

David

Terry_VK5TM · 30th Aug 2019, 9:48 am

And just so you can be spoilt for choice:

RS 775-7794 PET, Press Paper Elephantide Laminated Presspaper

ajgriff · 30th Aug 2019, 10:28 am

Quote:

Originally Posted by Radio Wrangler

I've always wondered just what fish have to do with it.

Wasn't there some story about it originally being used to wrap wet fish? Probably an old fishmonger's tale!

Alan

FrankB · 1st Sep 2019, 7:33 am

Fish paper comes in various colors and thicknesses.
When I need any, I go to my local electrical wholesale shop and they sell me some.
Other sources might be motor rewinders & transformer mfgr's.

stitch1 · 1st Sep 2019, 8:14 am

Quote:

Originally Posted by Terry_VK5TM

Yes, "Elephantide"

The use of ordinary cardboard is fraught with danger.

In damp/humid climes, it can absorb moisture and not only become conductive but it also promotes corrosion when in contact with metallic surfaces.

If you really, absolutely, must use cardboard, soak it in varnish or shellac and let it dry thoroughly before use.

Elephantide or Presspahn is still available. I restored a VHF81 and the service sheet said ‘slide the Presspahn heat deflector out’ but it was missing, I was pleasantly surprised to find they were still going and I ordered direct from them.

https://secure.presspahn.com/Cart/in...2g8li0aihgugg0

John

Boulevardier · 1st Sep 2019, 11:40 am

Quote:

Originally Posted by FrankB

Fish paper comes in various colors and thicknesses.
When I need any, I go to my local electrical wholesale shop and they sell me some.
Other sources might be motor rewinders & transformer mfgr's.

When I was looking for some on the web, it seemed much more readily available in the US than in Europe or UK. Can't think why...

Uncle Bulgaria · 2nd Sep 2019, 12:45 pm

Thanks for the tip, stitch1. Unfortunately Presspahn only sell brown (I happen to like the blue!) so it wouldn't match the Uhers, but the site looks an excellent source for all those materials I'm never quite sure where to get.

ajgriff - I hope they just used newspaper as this stuff seems rather too heavy-duty for real fish! Unless they needed the insulation for the stingray tails...

FrankB - this is where the US has some advantages over the UK. Here it's very rare to find such a shop, and they'll only sell lowest common denominator parts anyway. A real nadir was when I couldn't find anywhere in Brighton to buy good quality mains flex, an in-line switch and a good plug. I was reduced to Homebase with plastic packets of cheap and nasty pieces sold at outrageous prices.

ajgriff · 2nd Sep 2019, 2:01 pm

I'd guess that old fish wives would have sourced extra thin paper from the US.

Alan

Uncle Bulgaria · 8th Nov 2019, 11:01 pm

I got some of the RS Elephantide. It looks the part except one side has a very shiny plastic film on. I'm not sure if I'm supposed to leave this on or take it off - it doesn't peel off easily, and leaves a torn surface behind so it's not an adhesive protector.

The datasheet says '100% cotton' so is this some part of the process? The stuff already in the Uher is matt both sides, so I don't know if one side or the other is supposed to be 'hot'.

As it's just a shield so the broken main board doesn't touch the bottom cover it won't matter, but it might if I'm supposed to use it the right way round in a valve situation!

Terry_VK5TM · 9th Nov 2019, 12:48 am

Even the manufacturers don't specify which side is "up", so I guess it doesn't matter.

joebog1 · 9th Nov 2019, 12:58 am

Dad ( master rewinder and design engineer) always said shiny side to hi volts. I didnt ask, and he never said why.

Joe

Uncle Bulgaria · 9th Nov 2019, 5:39 pm

Thanks both. It looks like for this application, aesthetics wins out and it's shiny side down to match the rest.

Why I mind I don't know - who else is going to look inside the bottom of an old cassette desk and notice it?

Perhaps it's like Gaudi and the Sagrada Familia in Barcelona - on being asked by a bishop why he'd designed golden angels right up on the top of the spires where no-one could see them, he replied 'God will see them'.

29th Aug 2019, 9:54 pm	#1
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,330	Grey insulating cardboard Ahoy, In my Uhers there are rather fine pieces of thin, stiff, grey cardboard used between circuit boards and covers. Perhaps they aren't anything special, but they have nice pressed, smooth, shiny surfaces. If I wanted to use anything similiar in my own projects, or replace something in an old piece of equipment, does anyone know the name of this cardboard equivalent, or if it's something one can still buy today? Does it have ratings or did they just use bits of cereal packet?

29th Aug 2019, 10:12 pm	#2
MotorBikeLes Nonode Join Date: Dec 2012 Location: Kirk Michael, Isle of Man Posts: 2,350	Re: Grey insulating cardboard I dismantled so old battery drill batteries for cell renewal. They had similar card under and around the cells. I replaced it with card cut from a "hanger" out of a filing cabinet. The sort which slide in and out with the files sitting in the "cradle". try that. Les.

29th Aug 2019, 10:30 pm	#3
ajgriff Nonode Join Date: May 2004 Location: Halifax, West Yorkshire, UK. Posts: 2,587	Re: Grey insulating cardboard Is this a corrugated plastic material? If so, the brand name is Correx and sheets are widely available in different sizes. Probably something different. Alan

29th Aug 2019, 11:07 pm	#4
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Grey insulating cardboard This is the card I always use for those applications & more: https://www.jaycar.com.au/pressboard...erial/p/HG9985 It is around 1mm thick and for cardboard it has an amazing dielectric strength. It also looks very good varnished.Have a look at the battery case made out of it on page 12-13 of this article: http://worldphaco.com/uploads/USING_...CILLOSCOPE.pdf PS: the original card Jaycar supplied was a redish color, like that in the article, of late it has changed to a pale brownish color but it is electrically identical. Last edited by Argus25; 29th Aug 2019 at 11:15 pm.

29th Aug 2019, 11:49 pm	#5
kevinaston1 Hexode Join Date: Aug 2014 Location: Featherstone, West Yorkshire, UK. Posts: 386	Re: Grey insulating cardboard The thin grey cardboard is called FISH PAPER. It is used on a lot of stereo high power amplifiers, where the two amplifier channel boards have to be insulated from the metal cabinet. If you have a local Pro Audio power amp repair company, they may well have some. I had 20 sheets in stock in my department, before I was made redundant. I doubt it is still there, the new management who took over sent many thousands of pounds worth of parts to the tip. Kevin

30th Aug 2019, 1:03 am	#6
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Grey insulating cardboard Sounds like what I knew as "Elephantide"- a stiff grey-blue card like sheet material. Try this: RS Stock No. 775-7790 __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

30th Aug 2019, 1:16 am	#7
Terry_VK5TM Nonode Join Date: Oct 2010 Location: Tintinara, South Australia, Australia Posts: 2,339	Re: Grey insulating cardboard Yes, "Elephantide" The use of ordinary cardboard is fraught with danger. In damp/humid climes, it can absorb moisture and not only become conductive but it also promotes corrosion when in contact with metallic surfaces. If you really, absolutely, must use cardboard, soak it in varnish or shellac and let it dry thoroughly before use. __________________ Terry VK5TM https://www.vk5tm.com/

30th Aug 2019, 7:41 am	#8
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,330	Re: Grey insulating cardboard Once again, the hive mind comes up trumps! Looking at listings for 'fish paper' and the RS link, I think we've found it. As so often with the Infobahn the crucial thing is discovering the right search terms. I'll get some of this and compare it what I have. It's certainly more like cardboard than plasticard. Thanks all - don't worry Terry_VK5TM, I don't think I'll be desperate to put any projects in cardboard boxes! Shellac, however, is a lovely material with many uses...

30th Aug 2019, 8:03 am	#9
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,858	Re: Grey insulating cardboard Transformer winding firms are likely to stock fish paper in some of the thinner grades. I've always wondered just what fish have to do with it. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

30th Aug 2019, 9:48 am	#10
Terry_VK5TM Nonode Join Date: Oct 2010 Location: Tintinara, South Australia, Australia Posts: 2,339	Re: Grey insulating cardboard And just so you can be spoilt for choice: RS 775-7794 PET, Press Paper Elephantide Laminated Presspaper __________________ Terry VK5TM https://www.vk5tm.com/

1st Sep 2019, 7:33 am	#12
FrankB Heptode Join Date: Oct 2005 Location: Olympia, Washington, USA. Posts: 664	Re: Grey insulating cardboard Fish paper comes in various colors and thicknesses. When I need any, I go to my local electrical wholesale shop and they sell me some. Other sources might be motor rewinders & transformer mfgr's.

2nd Sep 2019, 12:45 pm	#15
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,330	Re: Grey insulating cardboard Thanks for the tip, stitch1. Unfortunately Presspahn only sell brown (I happen to like the blue!) so it wouldn't match the Uhers, but the site looks an excellent source for all those materials I'm never quite sure where to get. ajgriff - I hope they just used newspaper as this stuff seems rather too heavy-duty for real fish! Unless they needed the insulation for the stingray tails... FrankB - this is where the US has some advantages over the UK. Here it's very rare to find such a shop, and they'll only sell lowest common denominator parts anyway. A real nadir was when I couldn't find anywhere in Brighton to buy good quality mains flex, an in-line switch and a good plug. I was reduced to Homebase with plastic packets of cheap and nasty pieces sold at outrageous prices.

2nd Sep 2019, 2:01 pm	#16
ajgriff Nonode Join Date: May 2004 Location: Halifax, West Yorkshire, UK. Posts: 2,587	Re: Grey insulating cardboard I'd guess that old fish wives would have sourced extra thin paper from the US. Alan

8th Nov 2019, 11:01 pm	#17
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,330	Re: Grey insulating cardboard I got some of the RS Elephantide. It looks the part except one side has a very shiny plastic film on. I'm not sure if I'm supposed to leave this on or take it off - it doesn't peel off easily, and leaves a torn surface behind so it's not an adhesive protector. The datasheet says '100% cotton' so is this some part of the process? The stuff already in the Uher is matt both sides, so I don't know if one side or the other is supposed to be 'hot'. As it's just a shield so the broken main board doesn't touch the bottom cover it won't matter, but it might if I'm supposed to use it the right way round in a valve situation!

9th Nov 2019, 12:48 am	#18
Terry_VK5TM Nonode Join Date: Oct 2010 Location: Tintinara, South Australia, Australia Posts: 2,339	Re: Grey insulating cardboard Even the manufacturers don't specify which side is "up", so I guess it doesn't matter. __________________ Terry VK5TM https://www.vk5tm.com/

9th Nov 2019, 12:58 am	#19
joebog1 Banned Join Date: Jun 2015 Location: Mareeba, North Queensland, Australia Posts: 2,704	Re: Grey insulating cardboard Dad ( master rewinder and design engineer) always said shiny side to hi volts. I didnt ask, and he never said why. Joe

9th Nov 2019, 5:39 pm	#20
Uncle Bulgaria Nonode Join Date: May 2016 Location: Cornwall, UK. Posts: 2,330	Re: Grey insulating cardboard Thanks both. It looks like for this application, aesthetics wins out and it's shiny side down to match the rest. Why I mind I don't know - who else is going to look inside the bottom of an old cassette desk and notice it? Perhaps it's like Gaudi and the Sagrada Familia in Barcelona - on being asked by a bishop why he'd designed golden angels right up on the top of the spires where no-one could see them, he replied 'God will see them'.