Thursday, 8 December 2011

When Something Doesn't Quite Measure Up...

Self adhesive measuring tape
"A silvery, slithery, snake in the grass
perhaps? Or simply an inaccurate
peddler of measurements? Hmmmm..."

I'm still midst organising the new sewing room - and have been much distracted by a) a lack of lighting downstairs in our house due to an electrical fault (which is not good in the dark winter evenings, and it has taken up too much of our time on the weekends trying to fix it without paying £££ for an electrician to come out - luckily we managed to isolate the faulty part of the circuit and everything else apart from the kitchen now works again), b) trying to assemble a new garden shed + paint + felt it's roof + insulate it etc. etc., c) life in general and d) I transferred to a new job last week too ... phew! You get the picture - sewing has been on my mind, but not being actioned at all and my fingers are gettin' twitchy!

So, I decided to instigate a little drop of progress when I bought a self-adhesive measuring tape (approx. 150cm / 59" long) from MacCulloch & Wallis after work one day, for the princely sum of £1.95 (+ VAT). It's a silver coloured tape (polyester based I believe - it certainly feels very thin and not at all metallic despite it's appearance). I decided it would be very handy on the front edge of my cutting table (which is 150cm long from IKEA).

I cleaned off the surface for dust and grease (I swiped it with a dab of surgical spirit on a J-cloth to de-grease it and allowed it to evaporate off first to ensure good adhesion). I carefully applied the tape smoothing out bubbles as I went, and I took extra care not to apply to much stretch/tension on the end, so as not to elongate and distort it as I reached the end.
So, imagine my surprise when I saw this

150cm self adhesive measuring tape
What's not right with this picture? 150cm long table + 150cm tape measure... Answers on a postcard LOL!

Hmmm... see how on my 150cm long IKEA table (I checked!) the self-adhesive measuring tape seems to have stretched during the sticking down process and is too long by approx. 4mm?...

I considered lifting and reapplying it - but I thought it'd definitely not go down again so cleanly and would end up a nasty waste of time. So, I thought I'd check it against my fibre-glass based sewing tape measure (yellow). But, according to the yellow thing my table was 6-7mm longer than 150cm  - WHAT!?*!

Okay, by now I realised that one or both of the tape measures was inaccurate - so I compared them to some rigid rulers...

Comparing to my tape measure (at 20cm)

I comparing the (silver, at bottom of photo) self-adhesive measuring tape which I suspect is not accurate to the flexible tape-measure (yellow) and a rigid plastic ruler (45cm), and an aluminium metal ruler from the DIY store (100cm).

Attempting to line them up at the 20cm mark they are all pretty close - only the yellow one appears to be 1mm longer than the rest.

Next, I thought okay if the yellow 'n' silver ones ARE out of whack, then maybe it'll show up more at a greater distance (e.g. let's say the silver one was 1% too long - 1% of 10cm would be only 1mm, but at 100cm that's 1cm more - and easier to spot too).

Comparing to my tape measure (at the 100cm)

Comparing the tapes and ruler at the end of the 100cm aluminium ruler - the vertical clear ruler is aligned with the 100cm mark on the yellow tape-measure, but see how the yellow one seems a bit "short", and the self-adhesive tape (bottom) seems a tiny bit "too long" verses the aluminium ruler!!

Lastly, looking at the end of the table top...

Comparing to my tape measure (at the end)

Comparison at end of the (silver) self-adhesive measuring tape. The table is 150cm long, but the silver-coloured tape seems short! And yet, the yellow tape measure is also short - but by a different amount. Very odd! (NB: I carefully smoothed out the yellow one and held it in place lightly with sticky tape to get the photo.)

I have concluded that the self-adhesive tape and my yellow tape are inaccurate, and not to be relied upon for very detailed work - especially not anything over 20cm (haha). This got me a bit worried about some other rulers I have - but I checked those against one another and they seem fine (phew!).

Various rulers
A few of my rulers (I DO have more haha!)

I have heard that older fabric based tailors/dressmakers rulers were very prone to stretching and distorting - but that's not such a problem for the modern sewing tape measure (often made from fibreglass enclosed in plastic - like my yellow ones pictured many times above). So, my yellow ones shouldn't get any worse LOL!

I think the moral of this story is that a bad workman can't blame their tools if he/she doesn't check them first. Accuracy in sewing and pattern making is very important, and inaccurate rulers etc. could throw you off course without you even knowing. Imagine if you accidentally added 3mm to the edge of each seam allowance line on a 2-piece, A-line skirt zipped-up the centre-back - that could mean 4x side seam edges, plus (2x) either side of the zipper - 6x edges in total. 6 x 3mm = 18mm or approx. ¾" (that's assuming you didn't stitch it inaccurately too - which could compound the error eeek!). That's a big difference between a well fitting waistband or not!

Luckily for me, I don't plan to use the tape stuck on the table for accurate work. It's there to help me measure up approximate lengths of fabric / pattern paper / trims etc. and will save me time rummaging around for a tape measure when I need one :)


  1. Oh my!! I better check all my rulers and tapes.

  2. How crazy! Although I'm not exactly surprised. I really, really don't want to check the accuracy of my various tape measures...

  3. Wow, I wouldn't have seen that coming. I knew that some would stretch over time, now I'm wondering if mine are stretched. It's a different kind of "vanity sizing", eh?

  4. I don't think my yellow tape has stretched - I just think it's consistently inaccurate... if that makes sense! What I mean by that is that I think it's a certain % in accurate across it's entire length - but that it's only really noticeable as the length you want to measure increases (like my example above.. "e.g. let's say the silver one was 1% too long - 1% of 10cm would be only 1mm, but at 100cm that's 1cm more - and easier to spot too.")

  5. First of all what great thinking sticking a measure to your table.... But the trouble it caused! I'd never have guessed. I like your moral by the way!

  6. Wow! Although I never trusted the idea of sticky measuring tape. I'm off to check my rulers.

  7. This is crazy. I had already realised that two of my fiberglass measuring tapes were off. So decided to always use one. The thought was if I always use one it will always be off by the same amount. But the sometimes I use a ruler. I have some checking to do now. Accuracy is super crucial for me since I make my own patterns most of the time! Thanks!


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