Undoing metal cap on glass bottle

[brightncheerful]

DAK please the easiest/best way to undo a stuck metal top on a glass bottle of vegetable oil?

Picture here https://www.ocado.com/webshop/product/Crudigno-Organic-Flax-Seed-Oil/314364011

The top is in two sections that are joined before the seal is broken. The upper (larger) section is the screw top itself, the lower section is a ring of metal under the upper section. Turning/twisting the upper section is supposed to break the seal, but often it doesn't, so all that happens when the cap is turned is that both sections revolve. I overcome the problem by using a hacksaw blade to cut through the several joins but surely that's not what's done typically!

tia
BnC

[Watis]

This is what happends when the strength of the remaining bits of metal joining the two parts is stronger than the threaded part of the cap, which then stretches over the thread on the bottle as you twist it.

Your solution is the best one I can think of for this problem. An alternative would be to use pliers to hold the botom ring stationary - but carefully, to avoid crushing and breaking the bottle.

Watis

[jfgw]

Those caps are only aluminium. A sharp knife cuts through it easily.

Julian F. G. W.

[brightncheerful]

I used to use a Stanley knife but found that the blade kept slipping, even though I hold the bottle firmly in a horizontal position (the bottle, not me). The hacksaw blade has a serrated edge and is less likely to slip.

I have found that holding the bottom ring with pliers only works when there's enough space between ring and bottle for the pliers to grip.

This morning I used a hacksaw blade to cut through and then prized off the cap using a flat screwdriver. If it doesn't damage the upper section then the lower edge of the upper section ends up rough. I replace the offending cap with one whose seal broke as designed.

Mrs Bnc, for it is she that is responsible for undoing the metal cap in the first place, suggested that I return the bottle to the shop and get another one. A round trip of about 16 miles with no certainty, unless I open it whilst in the shop, that another one would work as intended.

[bungeejumper]

Oh, for goodness sake, just grab the cap with your teeth, give it a twist, and pull. It works for me. And on beer bottles too. What's wrong with some people?

[Slarti]

If my pliers won't grip the ring, I cut some of the lugs joining the cap to the ring with an old pairing knife that lives in my toolbox

Slarti

[Urbandreamer]

I used to use a Stanley knife but found that the blade kept slipping, even though I hold the bottle firmly in a horizontal position (the bottle, not me). The hacksaw blade has a serrated edge and is less likely to slip.

I too use a knife, but one that is more comfortable to use than a Stanley (Box/Ulitlty) knife. The trick that I find is NOT to place the bottle on a surface and cut away from you but to sandwich the bottle top between the blade and your thumb. You then apply pressure. DO NOT TWIST. You are attempting to use the knife edge like a wedge or the blade of an axe rather than as a knife. The edge of the steel knife will force its way through the aluminium to the glass. Remove the pressure and cairfully rotate to the next tab.

Works every time.

OK the next job is to sharpen the now blunt knife.

[genou]

OK the next job is to sharpen the now blunt knife.

Do you possess a corkscrew with a built in short blade for cutting foil? Might be a better bet going forward.

[pochisoldi]

Warm the bottle top under a hot water tap?

[Itsallaguess]

Amateurs, the lot of you....

http://www.instructables.com/id/How-ta- ... ss-Bottle/



Itsallaguess

[Breelander]

The bottom (detachable) part of the cap is supposed to be a shrink-fit so that it won't pass a ridge in the glass bottle. What's supposed to happed when you first undo the cap is that the cap unscrews, but the lower ring won't rise past the ridge, the cap then tears along perforation in the cap.

The are two things that can go wrong. The first is that the cap is too loose a fit, do the lower ring doesn't get held down by the ridge. The second is that the ring is held down, but instead of tearing the perforation the thread of the cap is stripped instead.

A precautionary weakening (or even breaking) of the perforations by rolling a sharp kitchen knife around the cap before the first attempt to open can help avoid both failure modes.

[richlist]

Packaging design......I often wonder how much effort goes into creating the rubbish packaging in supermarkets.
Why this type of seal is used at all is a complete mystery......don't recall ever seeing it in mainland Europe.....surely a paper seal over the cap would be sufficient ?

[Clitheroekid]

Maybe you need one of these - https://www.amazon.co.uk/dp/B01N417YZI/ ... il_2?psc=1

Other Easy Open Bottle and Jar Opener Arthritis Jar Opener for Seniors are available!

[6Tricia]

I have one of those CK, one of Lidl's offers a few years ago. It is brilliant - works for all sizes of jars and bottles. It is constructed of a soft to the hands material which makes it easy on my arthritic hands.

Tricia

[swill453]

Maybe you need one of these - https://www.amazon.co.uk/dp/B01N417YZI/ ... il_2?psc=1

I don't think that would help the specific problem here, which is that the bottom ring is so firmly connected to the cap that it makes the cap strip its thread (I believe).

Scott.

[brightncheerful]

Thank you for your suggestions.

It's Mrs Bnc that tries to undo the lid in the first place, not me.

As Scott right says of CK's suggestion, a grip for opening lids is not the issue. Mrs Bnc does have a gadget for that sort of thing, a square rubbery thing that enables a firm grip. For any airtight lids that are particularly resistant, my way of loosening them is to pierce the lid with a pointed screwdriver thing - such as http://dynamicsalescoinc.com/app/uploads/2016/04/awl-point.jpg - either by using brute force or banged in with a hammer.

Why this type of seal is used at all is a complete mystery.

In league with the hacksaw and knife manufacturers?

[Breelander]

For any airtight lids that are particularly resistant, my way of loosening them is to pierce the lid with a pointed screwdriver thing ...

I find a firm tap of the edge of the lid on a work surface loosens it enough to undo it.

[UncleEbenezer]

OK the next job is to sharpen the now blunt knife.

As a fellow knife-user, I have an answer to that.

This is a very different job to the usual usage of a regular kitchen knife. Use the portion of the blade immediately next to the handle. It gets blunt, but that really doesn't matter: it's more the centre of the blade that gets used for your onions or your bread.

Or just use a decent-quality table knife. One that's not sharp in the first place, but just about sharp enough for this job.