Hi Phil,

I get this all the time with old cased micrometers, it does not seem to matter what make they are although perhaps Mitutoyo are slightly worse than M&W.

All I do is blow the worst off and out of the cases; I use meths to clean the instrument and if really bad a gentle touch with very fine grade Garryflex block. Not much can be done about the staining.

For the case linings I have tried all sorts and latterly have settled on either the soft black padded vinyl that HALFORDS sell as boot lining OR the black non slip material that lines drawers. Both are good.

Using foam when you have a lot to do is abit of a faff as it does not cut well leaving ragged edges.

I use spray mount sparingly to stick the new linings in.

For larger cases I use adhesive backed sound proofing foam from EBay, cost very little and one lot will last me literally years and I do a LOT of cases.

Cheers, Martin

**LINK**

Plastazote®

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They learned their lesson, Vic.

MichaelG.

I had the same problem with my Thornton set. I remember the plastic hinges were on Tomorrow’s World and were supposed to be good for a million reversals. I have had the set since about 1970 and the hinges are still good but I had to replace the foam.

Mike

It's an issue with many plastics as the plasticisers evaporate, or migrate to the surface.

N.B I'm not a chemist, just an observer.

Rigid plastics get brittle, foam disintegrates, which might actually be the same process.

I'm guessing its more obvious with foam due to its much higher surface area. I wonder of the longer term solution is the old fashioned one and to use felt as a box liner.

The other really obvious problem with disintegrating foam, is in the compliant pars of loudspeaker cones. Rubber lasts longer, but the foam falls apart after a few years, especially if you live near the sea.

Fortunately this one is curable as kits are readily available to repair the driver units.

Whilst on the subject of HiFi, anyone with an old collection of vinyl would be well advised to check the inner sleeves. Many of those used to have a plastic liner to the paper inner, and it's now getting to the age where it's starting to break down.

The same problem that Philip has with his micrometer can also affect LPs, but in this case the damage is audible rather than just in appearance, and is harder and more expensive to cure.

Bill

Edited By peak4 on 27/01/2019 00:48:11

Seems many have the same experience! I have had the same problems in a number of applications using foam – Vinyl acetate based, as well as polyethylene (cross linked and none-cross linked) as well as polyurethane. I have tried so many types and am still trying! I use the foam as packing base for small unmanned aircraft in a largish rugged case – about 1.5m x 0.8m tall x 0.6m deep. I get maybe 2 years of life out of the stuff. It starts to 'powder' and if you grab hold of a piece and squeeze tigtly, it does not return to shape. If you squish it between thumb and forefinger is becomes pasty and sticky. These cases/aircraft are in use on the west coast of Namibia and are exposed to a lot of salty humidity.

I used a 'fancy' automotive foam, closed cell type – used to pad car engine cells/bulkheads to reduce transmission of noise into the cabin, and made a storage case for my 5C collets – that reacted so badly with WD40 that I oil the collets with before storage, and started becoming sticky and staining the collets. I would have thought that an automotive foam would need to withstand car engine oils/fuel spills etc – I obtained the foam from an automotive body manufacturer in Port Elizabeth in South Africa.

The problem is however not limited to foams..My Agilent oscilloscope ( a 4 channel digital storage scope, 5GHz sample rate, ie, not 'cheap'..) has most of the control knobs made from a nice tactile feel rubbery material. These have ALL become sticky and if squeezed likewise form a sticky malleable muck between the fingers.

My Infra red handheld thermometer has a rubberised coating on the handle and this after two years has become sticky to the extent it became disgusting to hold..Cleaned off the coating with thinners and it is usable again. Ditto the handle of my 'press to extract' wine bottle cork extractor…which was fine in Johannesburg ( no sea, salt and low humidity) and which went sticky after around 18 months at the coast..

No idea what to do about this – move to drier climes???

Joe

They should use the plastic that is filling our oceans, that seems most reluctant to degrade. Starrett used to just use a wooden box for larger mics but I have noticed many felt lined cases seem to hold moisture and are obviously in close contact with the item to be protected so promoting rust. It is vital that tools in cases should be kept dry and not subject to temperature changes that cause condensation. After making a wooden block to hold taper shank tooling I noticed that where the shank contacted the hole a rusty ring developed, I don’t think it was the wood but condensation would accumulate at the contact ring and the wood would absorb it and make a rusty ring. The rest of the drills stayed free of rust as they are slightly oily and dry quickly.

Mike

Edited By Mike Poole on 27/01/2019 10:36:46

You need to be aware that the plastic supermarket bags also disintegrate over time. We had some items stored in the loft in old supermarket plastic bags, when I went up to retrieve some items the bags just crumbled away in my hands, seems that the dry atmosphere in the loft caused them to disintegrate, shame the same thing doesn’t happen when immersed in salt water then perhaps our oceans may not be quite so polluted.

Dave W

Mitutoyo tools are excellent, but their boxes are rubbish. The cream coloured boxes that their micrometers come in are extremely brittle, i have several where they have cracked or broken, leaving the tools open to damp and dirt, not good.

The felt in the micrometer boxes, is in the lid, and yes i have several that have turned to crumb rubber, leaving the mic covered in little black specks.

I also have a metric mitutoyo depth mic, that came in a nice wooden box. It was in perfect shape, but i went to use it one day and was disgusted to discover the depth rods covered in rust. I had to clean them off and some were pitted. Things like wood and felt absorb moisture and rust tools.

Someone told me mothballs in tool cases resist rust, or maybe things like vp90, as used in gunsafes and things like that.

Tools in daily use are not going to suffer from adverse storage conditions but in the home workshop it is difficult to use every tool everyday so storage that keeps tools in good condition is important. Keeping precision tools safe in a workshop that has temperature and humidity variations is a challenge so maybe bringing them indoors to keep them in a warm and dry environment is a wise if inconvenient strategy.

Mike

Edited By Mike Poole on 27/01/2019 21:23:36

I've had the same problem with the foam liners for large Custom Cases. It seemed to lose resilience and turned into a sticky mass over about 30 years of use. I also found that the residue did leave some slight unsightly corrosion on the metal surfaces which took some time to clean off.

I have replaced them with a similar foam from the manufacturer as I thought I was just unlucky with the way the cases were stored, but now see that I shall have to keep a close eye on the condition of the foam in future.

Thank you for the timely warning to check all my micrometers and other instruments that have foam in the cases.

Neil