Photo 1: Airbrushed and pinstriped Tribal Celtic knots (in gold) on a custom cut fender

Many pieces of the Medieval Celtic Armored Triumph Rocket III project include Tribal Celtic designs that flow along nonlinear paths. Photo 1 shows the front fender from that project. This guide will focus on how to draw these types of knots (the gold patterns outlined in black) along irregular contours.

The completed designs may look complicated, but like most ornate Celtic artistry, the designs can be broken down, applied in discrete steps, and repeated again and again to achieve the final design.

This process is not a quick and easy way to draw Celtic designs. Their very nature requires time and precision to layout correctly. To give an idea of the time needed, the designs shown in Photo 1 took one and a half hours to layout and draw in (both sides of fender) and another one and a half hours to cut out for airbrushing. Then yet another 3 hours can be tacked on for the airbrushing and pinstriping stages so we can end up with the finished designs shown in Photo 1.


Break the Design Down

Photo 2: The basic unit of my Tribal Celtic Knot used throughout the project

Photo 3: Guidelines showing how we can break down the design

Once you sketch up a knot design that can be repeated and connected together, like shown in Photo 2, you have to break it down so that you can quickly draw it using a few reference points. This is important if you want your knots to flow along an irregular path. If your knots only needed to follow a straight line, then the task would be far easier - just create a freehand stencil of a portion of the knots and apply it in sequence - but to follow a non-linear path, we have to apply a little ingenuity.

Photo 3 show guidelines applied to the knot design at its most important points: Center guides (light blue), Horizontal guides for the pointed features (red), and Vertical guides for the pointed features (purple). Now I make note of the relative proportions of the guides so I can draw them consistently.

The middle red guide is at the one-quarter mark of the entire length and the two adjacent red guides are about one-third a length of their respective one-quarter sections. The vertical purple guides are at the one-quarter point of the entire width.

Now, even though I will be drawing guides for the lower portion of the knot when I draw the designs, I do not note them here because they are simply a mirror of the upper guides. Just keep in mind the same proportions as for the upper guides.


Prep the Surface for Drawing

Photo 4: Masking tape is applied to the areas where the designs will go. Then a "bounding box" is lightly drawn in to contain the designs.

At this point we should prepare our surface for drawing the designs. I use automotive grade, 2 inch masking tape to cover the areas where the designs will be drawn. You may use any masking material that you can easily draw on with a pencil, and if you need to follow contours that are under the tape then also use masking that is semi-transparent.

Make sure you lay your masking flat and get rid of bubbles and wrinkles. If your masking material is too rigid and wrinkles too much on curved surfaces like the fender, then overlay smaller sections like shown in Photo 4. The masking will lay flatter if it is partitioned. You do not want wrinkles or bubbles that could allow paint to bleed into unwanted areas.

Bound the Designs
Next we need to draw a bounding box to define the borders of our designs. It is best to use a ruler to mark off the bounding box at regular intervals instead of freehanding and eyeballing it. Any irregularity in the positioning can be easily picked up even by an untrained eye.

For curved surfaces like the fender, I like to use a cloth or tailor's tape measure so I can measure more precisely on contoured surfaces. For this fender, I drew dots every few centimeters, 2 cm away from the contour I was following (the edge of the airbrushed armor bracing) to define the closest border of the bounding box. For proper spacing of the dots, the tape measure should be held perpendicularly (90 degrees) at each point along the contour that is being followed.

Then I connect the dots and I have one side of the bounding box. Now I use that as a guide to make the opposite side of the bounding box using the same method. Once I have the two sides drawn, I draw in the short sides to close off the bounding box, again using the same method to follow the appropriate contours.

Partition the Bounding Box

Photo 5: The bounding box is partitioned for each knot in the design.

Now that we have the area where the designs will go, we need to figure out how many knots can fit in it and draw appropriately sized partitions to contain each knot. The easiest way to do that is to print out or copy the basic knot design (Photo 2) so that it is the same width as the bounding box. Cut out the knot and use it as a measure to count off how many whole knots will fit in the box. Make note of that number as the number of partitions you need.

To draw the partitions, first find the midpoint of the entire bounding box. Since it is curved, use string, a french curve or some other long, flexible device. Run your measuring device along the entire length and in the middle of the bounding box. Mark where your string/measure ends, straighten it out, and then measure it accurately with a ruler or tape measure. Note the entire length for reference.

Next, divide that length by two to get the midpoint measurement. Use your ruler to mark off that midpoint on your string and then lay down the string along the bounding box again. Note where you marked the midpoint on the string and draw a dot in the bounding box where it is. This midpoint is where the partitions will be centered and also where the designs will be centered.

Now, to draw the partitions, go back to the copy of the knot design that you counted the number of partitions with. Use it to mark off the length and the half length points of the knot design on your flexible measure or string. If the number of partitions you calculated is odd then match up the half way mark on the string to the midpoint on the bounding box and lay down the string to match the contour of the bounding box. Then draw partition lines at the end points. This will produce the first partition, centered in the middle of the bounding box.

If the number of partitions you counted is even, then the midpoint of the bounding box will be a border line between two partitions instead of the center of one partition.

Use the string measure in the same way to mark the end point and middle of the rest of the partitions. In Photo 5, the partitions are defined by lines and the middle of each has a dot.

To further prepare for drawing the knot designs, lightly draw in the centerline running through the length of the bounding box. This line should go through all the partition center dots.


Drawing the Designs

	Photo 6 shows the first steps for quickly drawing a knot in a partition by using the proportions from our breakdown of the design earlier. The red marks in Photos 6 and 7 show what was drawn at each step. Step 1: A partition with the center lines drawn. Step 2: The middle red guides in Photo 3 are drawn at the one-quarter marks of the partition.   Step 3: The "outer" red guides are drawn at the one-third mark away from the middle red guide. Step 4: The "inner" red guides are similarly drawn at the one-third mark away from the middle, but towards the center of the partition. Step 5: Dots are marked for the outside 'V' corners of the knot at the midpoint of the guides. Step 6: More dots are marked for the important features, all of which fall on the end a guide or at the midpoint of a guide so positioning them is easy.
Photo 6: Guides are marked off for the design
	In Steps 7 through 11, I use the guides and center lines to draw in the knot design. The guides make the process go relatively quickly and even if the partition box is curved, your design will also follow the curve if you create guides (Steps 2 - 6) appropriately within the partition. It is easy to get confused about which lines go over and under, so keep a copy of the complete design (Photo 2) handy for reference when you are drawing in the design. Now, all you do to complete the designs is to fill in each partition. You may have to revise and smooth out connection points between partitions so that the knots flow into one another better. Once you get to the endpoints, just close the knots with any closing design you wish. In my example, I just close the ends to a leaf point.
Photo 7: The guides are used to draw the design

	Once the designs are drawn, I carefully cut out them out using an Xacto knife and remove the masking that defines the inside of the designs.
Photo 8: The designs are cut for airbrushing
	Additional masking is layed down to protect the base against overspray. Then gold candy paint is sprayed on the cut designs.
Photo 9: Gold candy is sprayed
	Once the gold is done, I add a little black to the gold paint to get a dark gold for shadowing. Then using a freehand shield, I shadow the portions of the design that weave underneath. This is not a necessary step, since pinstriping will bring back the interwoven appearance of the designs, but this helps to accentuate the over and under nature of the knots even more. Again, it is a good idea to keep your design reference (Photo 2) handy so you shadow the correct areas. When the shadowing is complete, I use an Xacto blade and run it along the edges of all the masking. This is a time consuming step for Celtic Tribal designs, but will ensure that lifting will not occur when the masking is removed. Whether or not you want to do this will depend on your designs. Designs that have thin and detailed features like shown here are a good candidate for using the Xacto blade. It is far better to spend time breaking the paint film with a blade than to take off your masking, have parts lift and then have to re-do the entire process again. At this point, the masking can be removed, and further detailed can be added, such as pinstriped outlines or more shadowing, to complete the design.
Photo 10: Darker gold is used to shadow the interweaving portions