Watercolor paper can be quite expensive, so you want to get your pencil lines down right with few mistakes, because too much erasing and redoing lines can sometimes adversely affect the paper.
You can use a light box for watercolor painting, which is a great way to get line art onto paper precisely and without any erasing. You can do this by tracing a finished pencil line sketch onto paper.
In this article I’ll show you which light box to buy, what to look for in a light box or pad and then how to use the light pad of any size to trace even the biggest sheet of watercolor paper.
Should You Use a Light Box for Watercolors?
Let me quickly talk about why you should have a light pad in your tool kit. If you’re like me and you don’t put down the perfect pencil stroke the first time, then you’ll be erasing again and again.
When you put down a pencil line, especially if you’re a little heavy handed, you’ll make marks in the paper. If you then erase that line, that mark will be indelible. Grooves in the paper made by the pencil are permanent.
On top of that, erasing takes an ever so small layer of paper, depending on how hard you erase.
Obviously these changes to the paper will have an effect, not only on the next pencil line if you’re going over the same area, but your brush strokes and the texture of the paper when you paint.
Changing the texture of the paper will mean certain marks will show in your painting. Having a faint pen stroke show up is not great and should be avoided, unless it’s an effect you are seeking.
So to avoid this, it’s best to minimise the errors you make with your pencil lines to begin with. Tracing from finished pencil lines is the best solution to this.
One of the reasons I don’t use light pads is that I usually leave all my mistakes in the painting, so if I put down a pencil line wrong, I leave it.
But for certain work like technical line work, the pencil lines need to be perfect, and in this case I would use a light pad to get those lines down perfectly before I transfer them to the watercolor paper.
Which Light Pad Should You Get?
They’re not called light boxes anymore, that’s the name for oldies like me, who used to use them. Or rather, light boxes have been replaced by light pads.
Now there are plenty of light pad brands available that do an excellent job for affordable prices. There’s only really one notable brand, however the others are just as good.
Huion L4S vs MSRM for Watercolor Painting
Huion is the most popular brand amongst artists that like to trace, especially as Huion highlights their pad’s ability to illuminate through thick paper. The A4 size is probably the most popular size too, which is what I used to have before I gifted my Huion to a fellow artist.
But don’t feel you need to get a Huion, the cheaper alternatives are really just as good. In my honest opinion, I think they’re all the same light pads from the same factory with a different brand name stuck on. They look and feel exactly the same.
As someone who rarely uses this technique I later decided I still wanted one in my set of tools, so I opted for a budget version and I have not had any complaints.
So I got the MSRM light pad. There are a number of similar not well known brands supplying the exact same light pad. It’s very light weight and minimalistic.
Even if you use bigger watercolor sheets that doesn’t mean you need to get an A3 light pad which can be twice the price. I’ll show you how further down the article.
What You Need to Look for in a Light Pad
The main thing you need to look for with a light pad is that it has sufficient brightness to show the lines through the thickest of watercolor paper.
Good heavy watercolor paper is typically 140lb 300gsm, but you can get paper going up to 400lb 850gm, which is very heavy (and expensive!).
So if you regularly use the latter then you need to make sure you buy a light pad with sufficient illumination power to have even the faintest of lines show through.
You should also consider the portability. An A4 size light pad is perfect for travelling around with, and also not forgetting storing away.
An A3 light pad, while obviously much better than an A4 size for tracing on larger than A4 sheets, is way too big to travel with and will require more storage space, hence why I prefer A4.
How Good Are Light Pads for Watercolor Paper?
Let’s look at how effective the light pad is for different types of watercolor paper to see how well it will work for you.
This is the acid test to be fair. The heaviest paper I have is Arches, and it’s also the best watercolor paper in my humble opinion.
So you can barely see the pencil lines, and this is a hardness B, so harder pencils would be better. The best are dark lines like the Pentel brush pen.
Cass Art Jumbo Gummed Watercolor Paper (300gsm)
This is one of my favorite watercolor paper brands. It’s not the best, but it’s cheap and works well enough for my needs. It’s not 100% cotton like Arches, but 100% virgin wood pulp.
Even though the pencil looks faint here, in person it was very clear to see. The other ink pens were super clear.
This pad is acid free, and similar to Cass Art’s jumbo pad, this is not cotton, but 100% virgin wood pulp.
Not as clear from the photo, but the pencils are clear, but not as much as with the Cass Art paper.
This is my favorite travel watercolor book. It’s a bit thinner than the previous paper pads at 200gsm and is only 25% cotton. It’s acid free or neutral PH, archive quality ISO 9706 without bluing.
Not a surprise here, all the pens and pencils were clear and legible. Of course this is thinner paper.
Cheaper Alternative to Light Pads
When I got my first light box, it wasn’t the thin and light pads they are today, those light boxes used to be made from these huge wooden box contraptions with a white glass surface and a bulb inside.
Although relatively cheap, they were quite cumbersome especially in the larger sizes. Today they are now ultra light and thin, and no longer resembling a box, hence why they are called light pads as opposed to light boxes.
So to trace large pieces onto smaller and bigger watercolor piece paper, I would use a window and available sunlight. Yes it’s that simple.
You simply attach the lines to be traced over the watercolor sheet onto the window with masking tape and trace over.
The limitations to this are that you are limited by the available light, so you obviously can’t do this technique at night.
Another is the size and design of the window. It needs to be flat and large for all sizes. With windows, this is not always the case.
The main issue for me was that you have to work vertically. I would always find it difficult to draw in this position.
However, as an inexpensive option, especially if you don’t need to trace very often, this is a good technique to have handy.
How to Use a Light Pad for Watercolor Painting
If you’re set on getting the A3 light pad, which I would not blame you for getting if you have the funds and space, then using it for watercolor painting is relatively simple.
However if you follow my recommendation and get the A4 size light pad, which I believe is a better option, I’ll show you how I use it.
So if you’re painting on an A4 sheet, then it’s as simple as tracing on an A3 sheet on an A3 light pad.
But if you’re using an A4 light pad for a larger watercolor sheet like A3, then the tools you need are your light pad and some masking tape.
First take your finished pencil line sketch and place it under the watercolor sheet. Take 4 small strips of masking tape and place them on all four corners of the watercolor sheet, folding it over onto the back of the pencil sketch paper. Alternatively you can use large paper clips, but if you don’t want any marks in the paper then masking tape causes less damage.
Place the taped papers onto the light pad starting with the top left quarter and start tracing. As you reach the halfway point, you can then move the sheets across to carry on tracing until you have the entire top half traced in.
Repeat this either starting again from the left or right. And you’re done!
I hope this article was of use, let me know in the comments below if there’s anything else you need to know.
If it’s of interest to you, the sketches in the above examples can be downloaded for free in my Gumroad store.