Butt or Trap? Spot colours.
Submitted by Steve on Monday, 27 April 20094 Comments
This is first thing we think about when separating your design for screen printing.

Butt or trap registration? What are they?
- Trap Registration.
This is essentially an overlap. When screen printing on dark garments all colours require a white underbase to improve there opacity. Without the overlap there is a danger the white will still be visible at the edges of the colour printed on top. Screen printing on textiles is a tricky business and very slight movement can occur in the fabrics and the screens, especially when heat is applied (the white underbase needs to be flash dried before applying the colours, trap registration creates a margin for movement. If applied correctly the overlap will be barely visible on close inspection. In a programme such as illustrator you can take the underbase back using a stroke of 0.5 . - Butt Registration.
separations set up to register perfectly without overlaps. This type of registration is hard to achieve, but well worth the extra set up time on longer print runs on light Tshirts, especially when using water based inks. It helps to prevent bleeding of colours and the need to flash cure between colours. This type of separation can also be used when discharge printing. Butt registration requires a perfectly aligned printing press, if you have uneven palettes and worn registration pins you may want to stick with the afformentioned Trap registration.
The above information although relevant to all screen printing does mention movement and press inaccuracies, this is with the assumption that 99% of people reading this type of article probably don’t have access to modern precision machinery. Most professional screen printers should not experience any of the movement mentioned, and use of trap will be limited to white underbases only.

Hi, Yes I found your site interesting, Registration is always a Key factor, in all Printing, more so, for 2 plus multi colours and of course waiting for one to dry before you can apply the next, then shrinkage could occur. ?
also overlapping colours is great if you use a colour to blot the other out (as Black), but if you use a lighter colour, you end up from using 2 colours-you get 3 colours as from the overlap.
So to do a but up to a colour? must be hard? especially in, butt up same colour to the left and right of the 1st image colour, On a long run, with Humidity, that affects your stock.
At 58 years old, I used to be (redundant now, due to this Digital age) an Offset litho Print Machine Minder, on a SRA2 Kord, and printing reversed writing out of printing 4 colour half tones in opposing corners of the sheet guides, can and did cause real problems.
So you have “Trap Registration”, would that be an image of your work shone down as a still image, to place the next colour to print?
I am just interested, as your work seems interesting, as I give thoughts back to my old job.
Then I was always in my job, to turn out work only that I would like done for me, in that way I felt I was giving my best.
Hope you have not thought, what a nutter emailing in, it’s just pure interest from me.
All the best,
Lawrence.
Thanks for your comments Lawrence, artwork is key to a good print, I agree, the overlapping of translucent inks is a great technique for achieving more colours with less screens. Although screen and litho printing are worlds apart in some respects there are many principles shared by both that will never change, and although the computer age has transformed both industries quite dramatically, a bit of old school, hands on, know how never goes amiss.
Thanks for this article, It gave me some more insight in the printing process. As a designer for tees I’m trying to get a better understanding of these things so we can deliver the artwork in aprinter friendlier state.
A related question: Is there an optimum stacking order of colours?
For example: would you always print the lightest colour first and end with the darkest colour? Or the other way around? Or does it depend on the artwork?
We sometimes have photoshop designs where thin white linework overlaps bigger solid dark shapes, destined for, say, an orange tee.
I wonder how a printer would prefer to handle that?
Hi Esta
We generally print light to dark, there can be some variations on this. T shirt Printers always use two whites when printing plastisol inks on to darker shirts, a base white which goes under all lighter colours which might be altered by the underlying shirts colour, then a highlight white which is applied later or last in the sequence. In the example you mention the fine white lines could be applied on top of the darker colour, leaving it as a solid block. It is also possible to print the dark colour over a solid white leaving the lines to show through. It very much depends on the inks your printer is using and his machine/carousel set up. These variables have been dealt with in different ways by different printers, this is the reason many screen printers prefer to take care of more complex separations in house.
If you wanted to print using discharge inks, only one white is applied, there would be no layering of ink, so butt registration is required, and a very accurate press…I think an article on colour sequences is required, thanks for your comment, I hope this helps a little.
Leave a comment!
Discharge Printing »
Discharge printing textiles and T-shirts
Discharge screen printing is one water based solution for light prints on dark clothing or textiles. It ticks the environmental printing boxes, but it is not without it’s limitations. Firstly we would not use this …
Organic »
New organic products for 2011
A big change for Advertees in 2011, New website is very near completion with more emphasis than ever on T shirt printing, and all inclusive deals. Lots of new products have become available this year, …
screen printing »
Making way for new auto.
The arrival of our new 8 colour automatic is getting closer, but preparation for the machines delivery is nigh on impossible with our current workload.
The new machine will bring much needed added capacity, and make …
Speciality inks »
Soft feel T shirt prints and foil
When screen printing Mixed Martial Arts T-shirts soft prints are nearly always a requirement. Screen printed foil T-shirts are currently a common request.
So we are now offering foils using a phthalate free adhesive, when used …
t shirt printing »
Screen Printing of Water based inks
May has been a very busy month for us, this blog has only seen one post at the beginning of this month, as printing T shirts has been required from waking to sleeping. Our new …
True process or CMYK »
Mr Chuffiewuffie full colour organic T shirt prints
Some projects are simply a pleasure to work on, and Mr Chuffiewuffie and friends was certainly one of those jobs Advertees enjoy. These illustrations by Rob Wills seem to spread a little bit of happiness …
Using Index printing »
Index Separation Method for Screen Printing
There are several ways of achieving this, including transfer printing and direct to garment (DTG) printing. The most commonly used techniques for screen printing however, are index and simulated process. The following is an insight into index separations.
We have taken this photo of a handsome rooster and opened it in Adobe Photoshop.
water-based »
Port Eliot 2010 T shirt.
This weekend Port Eliot Festival plays host to a huge variety of creative talent, and as usual there seems to be something of interest for everyone.
Unfortunately for Advertees a consequence of this event is that …
WP Cumulus Flash tag cloud by Roy Tanck requires Flash Player 9 or better.
Most Commented