Monday, January 28, 2019

Fifty Shades of Gray

Let's talk lead. Well, actually graphite, but everybody still calls it pencil lead. In a previous post I talked about using mechanical pencils with Wild Gears and touched briefly on the variety of leads available.

If you're not familiar with grading of pencil leads, take a look at this excellent primer from Jet Pens. (TLDR: B is softer/darker, H is harder/lighter, larger numbers indicate greater hardness or softness. 10B is incredibly soft and dark, 10H is so light it's basically invisible. HB is "normal", between H and B, about like a standard #2 pencil. F is an oddball, sitting between H and HB.)

Aside from 2mm drafting leads used a lifetime ago when I took drafting class (and we actually drew things on paper), my experience with mechanical pencil lead has been limited to the Pentel brand. There are others. Some of them are probably quite good. Pentel is readily available and hasn't disappointed me so I've stuck with it. 

The most common sizes of lead are 0.5mm and 0.7mm, though you can also get 0.9mm, 0.4mm, 0.3mm, and 0.2mm. The greatest variety of lead hardness is available in 0.5mm. Pentel makes from 4H through HB through to 4B, plus F in 0.5mm. The same range, minus the F hardness, is also available in 0.7mm. As you go out from there the variety gets more limited and the leads are significantly more difficult to find, particularly if you don't want to pay an arm and a leg.

Speaking of price, let me divert a moment and talk money. All of these leads are sold in tubes of 12. The very common HB can also be found in tubes of 30, and Pentel has somewhat recently come out with a new line of leads called Ain Stein that come in tubes of 15 and 30, depending on the diameter. The tubes of 12 should retail for less than $2. Many places sell them for $1.25 or less. There are less than scrupulous merchants who will happily charge you for one tube what you should be paying for a box of 12 tubes. Some really good deals can be found on ebay, but so can some incredible ripoffs. Beware when shopping online and be sure you aren't paying for a tube what you should be paying for a box of tubes. 

If you want to experiment with pencil, the easiest place to start is 0.5mm HB. This is commonly available at every office supply store on the planet. If you shop wisely you can get a lifetime supply of 0.5mm HB lead for next to nothing. You can also get inexpensive mechanical pencils that are adequate for use with Wild Gears, particularly as a starting point. (More about pencils in a later post.) If you prefer a slightly wider line, 0.7mm HB is also very commonly available. 

So why would you want to buy more than one diameter and hardness of lead? As the title of this entry suggests, shades of gray. The pencil is putting down a gray line. The only variations you have available are width of the line and darkness of the line. Not technically "shades" of gray, but work with me.  



In this image a range of hardnesses has been used to produce a kind of shadow or ghosting effect that makes for a much more interesting drawing than doing the same thing with a single hardness. This was produced using the 120 gear set with a 24 gear in the 29 ring of the 120 gear inside a 128 ring, successively using spiral holes 1 through 7 of the 24 gear. (I will from here on write this as 128/120/29/24/1-7.) I used 3H, H, F, and HB leads. The diameters varied because I had a limited selection of leads available at the time. 

One thing I have just recently become aware of is that the apparent darkness of a lead is effectively related to the diameter of that lead. Everyone who's ever used a pencil is aware that if you press harder you leave more graphite on the page and the line you draw appears darker. This is due to greater pressure per area contacted by the point of the pencil. A corollary is that if you exert the same downward force on leads of different diameters, the lead with the smaller diameter will exert more force per area contacted and therefore draw a darker line. 

Some simple geometry tells us the 0.3mm lead has less than half the contact area of the 0.5mm lead, so equal downward pressures on both will result in more than twice the pressure per square millimeter with the 0.3mm lead. Roughly the same relationship holds between the 0.5mm and the 0.7mm leads. The upshot of this is that if you exert the same force on a 0.3mm, a 0.5mm, and a 0.7mm pencil, all with the same hardness lead, the 0.5mm line will be darker than the 0.7mm line, and the 0.3mm line will be darker than the 0.5mm line. Unless you're very adept at changing the pressure you exert on the pencil, harder 0.3mm leads will appear the same or darker than comparatively softer 0.5mm leads. 

Here's a simple example.



Starting with the outermost loop and moving inward we have 0.7mm 3H, 0.5mm 4H, 0.7mm 2H, 0.5mm 2H, 0.3mm 2H, 0.7mm H, 0.5mm H, 0.3mm H, 0.5mm F, 0.7mm HB, 0.5mm HB, 0.3mm HB, 0.7mm B, 0.5mm B, and 0.3mm B. I tried to use as little pressure as possible on the pencil and helped the gear around the corners with my other hand so I didn't have to apply too much additional pressure there. Without the impact of the diameter of the lead this should result in successively darker lines working from the outermost loop inward. But close examination shows this isn't actually the case. It's easier to spot the differences on the gently sloping portions rather than on the tighter loops. 

Here's a closeup of one section.



I've added labels for some of the lines to indicate the diameter and hardness of the lead. The topmost marked lines with the H hardness lead probably demonstrate the concept best of all. The 0.5mm line is somewhat darker than the 0.7mm line and the 0.3mm line is clearly darker than either the 0.5mm or the 0.7mm. 

This isn't to say you should prefer one lead combination over another on this basis, but that if you're going for a gradient of gray in your drawing and intend to mix lead diameters you need to be aware that the narrower leads will draw a darker line than wider leads of the same hardness. 

So should you rush out and buy a tube of each lead size and hardness? Probably not. To start with, 2B and up are very soft and probably not suitable to use with Wild Gears except in very specific circumstances. They'll leave a lot of loose graphite on the page and result in smearing as the gear travels over the loose particles. You'll also burn through it very quickly. In my experiments I've found I have to advance the B+ leads every four or five loops on larger drawings, while HB will lay down a couple dozen loops without needing to be advanced. On the soft side I wouldn't go beyond B until you get some experience and know for sure you want a softer lead. 

On the hard side of things, 4H and 3H in 0.5mm and larger are very difficult to see and are only suitable for creating a ghosting effect. You could easily get by without these even with an otherwise complete set of leads. Since 0.3mm writes so much darker 3H and 4H would probably be of more use there (and if I can ever get some in hand I'll be able to speak more authoritatively on the matter). 

Obviously, the larger the diameter of the lead, the wider the line laid down by that lead. This can have a distinct impact on a drawing. 



This was drawn with 0.5mm F lead. (176/120/29/23/1)

Here's the same pattern but with 0.3mm 2H lead.



The narrower lead produces a much crisper looking drawing and makes some of the more complex features more clearly visible. Note also that even though F is two grades softer than 2H and should produce a darker line, the narrower 0.3mm lead actually looks considerably darker. I wouldn't say this makes one better than the other, they're just different. Which you choose depends on the effect you want to achieve. 

I would also add that the narrower diameter 0.3mm lead is consumed much faster than 0.5mm or 0.7mm. This has both an economic and a practical impact. The 0.3mm lead is more expensive than the others to begin with. Combined with the much higher burn rate and I'd say it's four to six times as expensive to use 0.3mm compared with 0.5mm or 0.7mm. I don't tend to experiment a lot with the 0.3mm leads. None of this is to say using pencils is expensive. Quite the contrary once the cost of getting the pencils is defrayed. But comparatively the 0.3mm lead will be much more expensive to use than the larger diameter leads.

From the practical side, using 0.3mm lead means advancing the lead in the pencil much more often than is required with the larger diameter leads. The softer 0.3mm leads can require advancing literally every few loops. This can be bothersome with more complex drawings like the ones immediately above. With the 0.5mm F lead I had to advance the lead maybe twice during the entire drawing. With the 0.3mm 2H lead I had to advance it at least a dozen times. Not a huge deal, but something you need to keep an eye on or you'll start dragging the metal shaft across the page. 

So, do I have a favorite? I wouldn't necessarily call it a favorite, but the one I turn to most often when trying new designs is the 0.5mm F. I like this hardness since it's hard enough that it leaves almost no graphite dust on the page yet it's still dark enough to be readily visible. Some of the harder leads can be very difficult to see if they're used entirely by themselves. It also doesn't hurt that I stumbled into a fantastic deal on a multi-lifetime supply of 0.5mm F lead on ebay.




1 comment:

  1. Beautiful explorations! Thank you for writing in such detail. That first pattern is stunning with the fade effect.

    ReplyDelete