Precision tool storage

[Ian Owen NZParticipant @ianowennz]

I have some Mitutoyo micrometers that are stored in the original boxes, some plastic, some wood.

A while ago I found the foam liner in the lid and under the tools starting to deteriorate and stick to the micrometer. Luckily, I caught it early enough that no real damage occurred and the minute rust was cleaned off with steel wool and WD40. After that I check all my other Mitutoyo storage boxes and found the foam starting to deteriorate in some but not others, so to avoid a costly outcome I remove the top and bottom layers of foam.

After googling this phenomenon, I found it happens and usually the outcome is permanently rusted/ruined tools

What to replace the foam with is the question, I thought maybe felt and found some wool felt and even Merino wool felt made here in NZ.

So I thought before I purchased anything I would do a search and ask the question, after searching I find comments to avoid wool felt and others saying it’s ok. I see Gerstner use a 100% acrylic felt with sizing to add stiffness. When looking for felt I find Wool, Wool blend, Acrylic and other blends then there is Baize which is different to felt………..talk about confused.

What would be best to line the Mitutoyo boxes with? Felt or Baize, wool or wool blend or synthetic?

 

I have attached a photo of a Moore & Wright set of micrometers, still new in the box which someone (I assume) has partially lined with felt

 

Thanks

Ian

[Speedy Builder5Participant @speedybuilder5]

You need to use them more !  The Silica Gel packets are more than likely ‘spent’ and now contain moisture – either chuck  them away or re-juvinate them by placing in a gentle oven for a couple of hours.  Also use VPI paper

VCI Paper

like this and change that regularly.  Too much WD40 etc soaks into the felt and in the end it rots out which will eventually turn around and absorb moisture. I guess from your location that you fight moisture all the time and that the best way is to try an fight that to protect all your machines and equipment. Perhaps de-humidifiers / air con is needed, but at a cost !!

Good luck

Bob

[Robert Atkinson 2Participant @robertatkinson2]

The problem is Polyurethane foam which degrades to an acid mess. Best removed with Methanol. Well know to users of precision electronic RF test equipment that uses the same foam.
Best replaced with polyethylene foam like this https://www.ebay.co.uk/itm/394001715305 Also available in two colours for a shadowboard effect https://www.ebay.co.uk/itm/388153901932?
A cheaper alternative is PVC foam somtimes called foamex. The waxy looking foam sometimes found in packaging seems to be a closed cell Polyurethane and does not seem to degrade the same way.

Robert.

[Charles LamontParticipant @charleslamont71117]

Felt is a random mat while baize is woven, and is the more traditional choice for drawer and case lining, such as for guns or the tool drawers in your luxury vintage motor.

Experimentally, the micrometer drawer in my tool chest is lined with a scrap of mat black plush velvet, which seems to work well and looks very posh.

[Michael GilliganParticipant @michaelgilligan61133]

For convenient reference … here’s a previous discussion:

https://www.model-engineer.co.uk/forums/topic/micrometer-woes/

Unfortunately, on that occasion I managed to offend someone … but the factual content remains valid.

MichaelG.

 

[noel shelleyParticipant @noelshelley55608]

I was given a set of 1/4″ drive Snap On sockets as a gift that looked so good they were kept for special work in a clean area = seldom. I used a spare steel box and lined it with expanded foam. The set included 2 black plastic handles. Not used for several years, one day I opened the box to find the area round the 2 handles had been broken down, all the tools chrome destroyed and heavy with corrosion and a very strong smell of Acetic acid. It appeared the source of the acid was the plastic handles. The only way I could stop this was to place the 2 handles in polythene bags but it did nothing for my beautiful tools now damaged ! Anybody else had this problem ? Noel.

[Michael GilliganParticipant @michaelgilligan61133]

Not specifically, Noel … and I don’t have the knowledge to explain the chemistry

but it sounds like a plasticiser used in the material of the  handles has migrated into the foam.

MichaelG.

.

Rabbit-Hole: https://en.wikipedia.org/wiki/Plasticizer

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, my Mitutoyo 25-50 mic, has been living in its humble plastic box for 25+ years, and hasn’t got any signs of corrosion, although the piece of foam has produced some dust, and gone a bit thin and split in places, although I do keep a couple of small silica-gel packets in with it.

My M&W 2″-3″ mic, and 0″-6″ depth gauge mic, are in wooden boxes, and although they have the sins of their age, there’s no real amount of corrosion to find on them, but I do keep a piece of VCI paper, covering them.

Regards Nick.

[SillyOldDufferModerator @sillyoldduffer]

First mistake, maybe, was buying a set of Snap-on tools and not using them!  Their value is being made to take a beating in a busy workshop, not kept for special occasions.  I say maybe because, even though it smacks of Gollum and his Precious, I too have some tools “kept for best”.   And my brutal view that tools are disposable, and only what they make matters, is unusual!  So I reluctantly admit collecting them is allowed too – this is a hobby, done for fun!

The second mistake was using a steel box for long term storage.   They encourage condensation and condensation is nasty.   Wet air penetrates deep into the microscopic pores of metals and leaves highly oxygenated and mildly acidic droplets in the most vulnerable places.  Gets behind paint, plating, and oiled surfaces.  And although the box allows damp air in, it, and the foam, both trap corrosive gases inside.

Third mistake was using an unknown foam for long term storage.   At least 5 different plastics are used to make foam, and, how stable the foam is varies considerably.   There are thousands of variants, many of which decompose corrosively.  They emit Acetic and other acids, plus organic fumes that can attack other plastics. As well as the plastic, manufacture might leave traces of anti-polymerisers, some of which are nasty, and then plasticisers are added to alter the properties of the plastic; these too can decompose.  Cheaply made plastic is only intended last 5 to 10 years, and it’s liable to contains aggressive additives.  The Chrome plating might have been another gotcha!   Chrome is used as catalyst when making some plastics, so the sockets may have accelerated the decay process.

What to do:

• Select a box that’s either completely sealed or well-ventilated and kept in a dry place.
• Completely sealed is best, but extremely difficult to achieve.  Therefore, use silica gel and vapour paper to slow down bad behaviour inside the box, and change them regularly.
• The box must made of something that doesn’t encourage condensation, either wood or plastic.  Again, be careful: not all woods and plastics are suitable.  Oak is often recommended for tool chests but of the 300 oaks sold to woodworkers, about half are acidic.   Cardboard and paper have the same problem – must be acid free.
• Select a foam, or other material, with known long term storage properties.  As I’ve found it difficult in the past to identify suitable plastics, I lean towards pure wool felt, which has proven good for years.  But this may be prejudice – there are plenty of folk on the web selling “tool box foam”, and in an ideal world they would all employ competent chemical engineers!  Buying pure felt might tricky – many modern fabrics are improved with synthetics, and the seller might not know.
• Or apply military style triple layer packaging, vacuum sealed, with the tools caked in Renaissance Wax! Or Cosmoline, horrible stuff…

Dave

[Trevor Drabble 1Participant @trevordrabble1]

Suggest you also speak with Shadow Foam in Norwich.  No connection with company .

[Howard LewisParticipant @howardlewis46836]

When the foam has deteriorated in my boxes, I have replaced the foam with layers of kitchen roll.

This does not appear to be acidic, since no corrosion has yet become evident.

The instruments are protected from vibration, The bare boxes used by M & W, of old, seem to be ideal, so maybe, no need for the foam, once removed, anyway.

Howard

[PeteParticipant @pete41194]

I agree with a lot of what’s already been mentioned.

I also believe that the foam degradation and especially the type Mitutoyo uses might have a lot to do with a combination of temperatures, maybe caused due to certain environmental conditions, humidity levels, and with possible further effects due to incorrect or even too much lubrication. For the metrology tool manufacturers, that foam most seem to use today is fast, cheap, easy to cut, and produce in volume production levels. Anything that might happen many years later may not be even considered. What does seem odd is many report issues with that foam degrading, so that much is well proven. And yet some like myself seem to have never had it happen. And I’ve got one micrometer I bought at least 40 years ago where the foam is still fine. One example proves nothing, but it may not be related to the materials age or lifespan. So something must be quite different between the two completely different results. The M.E. magazine ought to do a survey for what lube oils, WD 40 etc are being used, average humidity levels, controlled temperatures or not for those that have or haven’t had the same problems.

I’d guess Gerstner are now using that synthetic felt for cost cutting reasons. During most of there corporate history, they specifically mention using 100% wool felt in there tool boxes.

I bought my natural wool felt from a bricks and mortar fabric store. As soon as I mentioned what I was using it for they knew exactly what I wanted it and had it on the shelf. And that Merino felt is supposed to be the best. I’ve read that the natural wool felt retains some of the sheep’s natural oils even after it’s processed. That’s supposed to help with and prevent rusting, although it’s not completely immune to moisture absorption. Since it’s a proven material, it’s what I’ve used. But if I did have serious tool rusting issues, I think I’d buy the better desiccant packs that can be heat dried every so often and have at least one in all of my tool storage boxes.

Most museums seem to use the same wax Dave mentioned, but afaik, it’s meant for static conditions and fairly long term preservative reasons. For some items, I just use the much cheaper and easier to get automotive paste wax since it should be a bit more resistant around our lube oils. Used correctly, I think automotive paste wax works quite well for preventing rust. It’s just not all that durable, so it shouldn’t be expected to last for years.

 

[VicParticipant @vic]

Closed cell foam should offer protection without absorbing moister like felt etc. it’s probably what I’d use if the foam in my boxes breaks down.

[bernard towersParticipant @bernardtowers37738]

I have used rhoacell for the cutouts before and then lined them with green cloth from snooker tables. It seems to work well.

[Nigel Graham 2Participant @nigelgraham2]

I have seen similar with cases of drawing instruments.

The liner does not need be foam or fabric though neoprene foam might suit.

For years precision squares, micrometers etc were sold in wooden boxes. Cut the nest from good-quality plywood, sanded smooth and treated with polyurethane laquer so the wood does not absorb moisture or emit anything acidic that might corrode the tool.

Alternatively, cut it from PVC or similar, soft but semi-rigid plastic.

Cut generous recesses for your fingers to grasp the instrument.

[Nicholas Farr]

On Nicholas Farr Said:

Hi, my Mitutoyo 25-50 mic, has been living in its humble plastic box for 25+ years, and hasn’t got any signs of corrosion, although the piece of foam has produced some dust, and gone a bit thin and split in places, although I do keep a couple of small silica-gel packets in with it.

My M&W 2″-3″ mic, and 0″-6″ depth gauge mic, are in wooden boxes, and although they have the sins of their age, there’s no real amount of corrosion to find on them, but I do keep a piece of VCI paper, covering them.

Regards Nick.

Thanks for the reply Nick and I can say some of my Mitutoyo micrometers have been nestled in the original foam for more than 35+ years with no problem, till I found my 50-75mm mic corroded on the thimble. I had used it 3 months previously and hadn’t noticed anything. After doing a google search I found a number of references to Mitutoyo tools corroding due to the deterioration of the foam.

Since finding that out I removed all the crumbling foam from the boxes before it can cause any further issues.

Noel, sorry to hear about your Snap On 1/4 drive socket set, these are some of the best quality tools you can own, I’m sure the price is related to their warranty as I’ve made a number of warranty claims over the years and the tools were replaced without question……….not like a lot of other tool manufacturers.

But I digress, there is a lot of information in this thread, and like most problems there is more than one solution, so thank you everyone for your input

 

On 17 May 2025 at 09:31 Charles Lamont Said:
Felt is a random mat while baize is woven, and is the more traditional choice for drawer and case lining, such as for guns or the tool drawers in your luxury vintage motor.

Experimentally, the micrometer drawer in my tool chest is lined with a scrap of mat black plush velvet, which seems to work well and looks very posh.

 

Charles I have a Mitutoyo 0-1″ micrometer in it’s original steel case with what looks like Blue velvet in the case, this micrometer has never shown any signs of deterioration, neither have my other precision tools, just the one that was nestled in it’s original foam.

There was a period when the humidity in the workshop would have been quite high (perhaps I will write a story about that sometime), this was a year or so before I found the corrosion/staining on the micrometer. Perhaps this contributed to the issue, but it was only that single micrometer the others that had the foam in the cases I found the foam decaying and crumbling so removed it before it could cause an issue.

Now I’m looking for a solution, I don’t want the solution to cause problems in the future which is why I’m posing the question here and I’m sure I will find a solution where the materials I need are available locally and I won’t have any issues with corrosion in the future.

Regards

Ian

[Neil LickfoldParticipant @neillickfold44316]

In 2002 ,I replaced the foam in my micrometer cases, with an Antistatic  Foam that cam with some motherboards at the time. It is still good 23 yrs latter. The Mitutoyo original foam in the top side of the cases didn’t even last 10 years. Not sure if it is the residual oils in the air that does the damage or the foam just breaks down anyway. I suspect the latter.

I have no idea where to get that sort of foam today.

If anyone has a link to an antistatic foam like they had in the early 2000’s would be nice to be able to get more for tools that I have bought since 2009. For these ones, I have thrown away the original foam when it starts to go soft.

 

Neil

[larry phelan 1Participant @larryphelan1]

As they say, “If you dont use it, you lose it “!

[noel shelleyParticipant @noelshelley55608]

Further to my post on the issue with Snap On tools ! Daves comment about being for heavy work – the set ran from 9/16″AF down to about 1/8″AF, more for instrument work. The expanded foam, white of the type used for packaging is fine & about 40 years old, only in the area where the acid from the handles was did it break down and the tools rust. They are kept in the house so fairly dry. I used the same material to line a storage box for a set of taps and dies by carving the shapes needed, again 40 odd years ago, grubby now but still fine. I also had mitutoyo mikes that the foam just turned to powder but no corrosion. Noel.

[HollowpointParticipant @hollowpoint]

If you want my advice, don’t bother with anything. Keep your tools well oiled and in a plastic box.

Wood, paper, foam, felt, rag or whatever, the whole lot just acts as a huge sponge that traps moisture against metal parts.

I’ve seen countless tools ruined from trapped moisture. I’ve even seen tools rust as a result of being next to damp vci or waxed paper which is meant to protect them. 🙄

For longer term storage use rocol green guard spray and wrap in cling film.

[Author]

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