When a pattern says “5mm picot” what is the image that immediately comes to mind? A picot that stands vertically 5mm above the line of stitches, right? But a picot is an arch – a single length of thread that has been pushed back into a doubled-up loop. Thus to get a 5mm high picot we actually require 10mm long thread.
For exact measurements, we need a tool called picot gauge. In earlier times a tatting pin was used for this purpose. Now we use a flat rectangular strip which can be homemade or purchased, made out of wood, metal, cardboard, or plastic.
A gauge can be held in 2 ways to give us a final picot, equal or half in size.
Vertical and horizontal are two terms that are associated with picot measurement. These may refer to:
I. the picot gauge – whether it is oriented vertically or horizontally, or
II. to the measuring side of a picot gauge in relation to the core thread.
I. Orientation of Picot Gauge
Commonly, purchased gauges are fairly standard flat rectangles – tall & thin or long and narrow. In the images below, we can see both a homemade and a purchased picot gauge at work.
I.A. Horizontal Picot Gauge:

Fig1

Fig2
Here the long side of the gauge is laid over the stitches horizontally. Thread is looped over, next stitch made and pushed back. This double thread gives us a fully formed picot of the same size. In this position, multiple picots can be made and held on the gauge (Fig1). Fig2 shows a single 5mm picot.
I.B. Vertical Picot Gauge:

Fig3

Fig4
Here the long side of the gauge is held vertically, we are measuring a single length of thread and when the picot is pushed back, it will be half the size. In Fig3, black is the core thread and the picot thread is behind the gauge. The 5mm gauge will now give us a 2.5mm picot. Thus, for a 5mm picot, we need a 10mm gauge (Fig4). At a time, only one picot can be made with this orientation.
Purchased gauges are standardized and inflexible. But homemade gauges can vary, depending on the immediate requirement. What if the gauge is wider than it is tall as in Fig5? Is it now horizontal or vertical? In Fig6, is the gauge vertical? Will the resultant picot be equal or half the gauge? Fig7 shows a stepped gauge. Which side of the gauge is horizontal/vertical?

Fig5, Fig6, and Fig7.
As you can see, the orientation of the gauge – vertical or horizontal - is not always clear or universal. Instead, the measuring side of a gauge is what matters and gives us a consistent way of addressing how the gauge is oriented.
The number and arrow painted on a gauge denotes the ‘measuring side’ – the functional part of any gauge. When taking measurements, how the threads (core and picot threads) are held in relation to the measuring side is more important and reliable.
Thus, the focus has now shifted from the tool to what is being measured. Jennifer Williams has diagrammed this transition with clear instructions in ‘How to Use a Picot Gauge’.
Core thread is the only constant during measurement.
It lies flat (horizontal or on the X-axis) irrespective of the picot thread or the picot gauge.
II. Orientation of Picot Measurement in Relation to the Core Thread
We take 3 FACTORS into consideration – the core thread is a constant; the picot thread and measuring side of gauge are the two variables.
II.A. HEIGHT or Vertically Measured Picot:
Coming back to the question at the beginning, there is no ambiguity about what a ‘5mm picot’ is. We all see a finished picot as a doubled-up thread that stands at a 90 degree angle (vertical) to the stitch. Hence, the finished picot measurement is the height – how high/tall the picot stands above the core thread or line of tatting.

Fig8
In Fig8, we have draped the thread vertically around (front and back) the 5mm or the measuring side of the gauge and hence the height of the finished picot is the same. During measurement, the picot thread lies perpendicular to the core thread.
II.B. LENGTH or Horizontally Measured Picot:

Fig10 – holding gauge below core thread rather than above
• Decorative Effects -
The gauge is conventionally held between two half stitches. In some effects, the gauge is inserted through the leg/loop of the next half stitch being formed. It can be held above the core thread, or below the core thread (Fig11) as in an inward picot or in a tuft picot, either in first or second half stitch.

Fig11 – Antonina Caruso’s Inward picot and Tuft picot
RECAP
1. While making a measured picot, the core thread always lies flat/horizontal.
2. The picot thread always lies perpendicular to the core thread, either above or below it.
3. The picot gauge lies parallel or perpendicular to the core thread, either above or below it.
Experienced tatters use the concept without any difficulty, sometimes instinctively. Terminology is where confusion abounds - what does ‘vertical’ and ‘horizontal’ refer to? It is important for the designer to communicate clearly (and visually, if possible) without ambiguity.
To conclude, in order to form an accurately measured picot, we can use a picot gauge to either:
a. measure the length of picot thread
b. measure the height of the picot
c. measure above or below the core thread
d. measure between or within a double stitch
This article is based on a discussion between Georgia Seitz, Robin Perfetti, and muskaan.
Images courtesy Georgia, Robin, Coretta Loughmiller, muskaan. May, 2018.
Reference:
Elgiva Nicholls, book- ‘Tatting Technique and History’ 1962
Judith Connors, book- ‘An Illustrated Dictionary of Tatting’ 2007
Georgia Seitz, article- ‘Picot Gauges for Perfect Picots’
http://www.georgiaseitz.com/gauges.html
Jennifer Williams, pdf- ‘How to use a Picot Gauge’
http://www.cariad-tatting.co.uk/page3.html
Robin Perfetti, blogpost- ‘Orienting a Gauge’
http://tattingbythebay.blogspot.com/2017/10/calculating-height-of-beaded-picots.html
Antonina Caruso, blogpost & video- ‘Tatting the Tuft Picot’
http://ninettacaruso.blogspot.com/2017/08/video-posted-tatting-tuft-picot.html
muskaan, blogpost- ‘Picot Gauge in relation to Core Thread’
https://tipsaroundthehome.blogspot.in/2017/08/gauging-lie-of-land.html
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