Patterned (and Textured) Shirts
As long time readers may know, I’m a graduate student in his mid-30s, and I teach and study at a research university located in the Bay Area, a region somewhat known for its casual culture. One way for me to dress down my usual sport coat and wool trousers ensembles is through patterned shirts. If solid blue shirts are a good alternative when white is too formal, then patterned shirts can make things more informal still.
There are two basic patterns for shirts – checks and stripes, with each having varying degrees of casualness. The rule of thumb is that the bigger or bolder the pattern, the more casual the shirt is considered. For example, madras and gingham are more casual than graph check or tattersall. Gingham is that “picnic table cloth” pattern you see here, and madras is the colorful Indian interpretation of Scottish plaids, which we’ve covered here. Graph checks and tattersalls, on the other hand, are a bit more conservative, with the first looking like … well … graph paper, and the second looking like two or three graph checks overlaid on top of each other. Gingham and madras should probably be reserved for weekends, whereas graph checks and tattersalls can be acceptable in more casual office environments. In the fall, I think they can look especially smart under “textured” sport coats, such as ones made from tweed or flannel.
Stripes follow similar principles. A hairline stripe, which you can see above, is when the stripes are so close together than they resolve to a solid when viewed from a distance. As I write this, I’m wearing a light blue hairline stripe shirt with taupe tropical wool trousers and a patch pocketed navy sport coat. On some level, perhaps a light blue candy stripe or Bengal stripe would have been better, since I’m also wearing loafers. That way, the casualness of a bolder stripe would match the casualness of the shoes. Candy stripes are usually about 1/8” in width, whereas Bengals are a bit wider at 1/4”. Those along with dress stripes (also known as pencil stripes) are the three patterns I wear the most.
Of course, I still think you should have a strong foundation of solid blue shirts. Depending on your lifestyle, those will probably be the easiest to wear. However, I will say that I only own two solid blue poplin shirts, and don’t plan to get any more. I’ve found that lacking a pattern, solid blues tend to be more interesting in something that’s not a simple plain weave. End-on-end and chambray, for example, have a nice criss-crossing mix of blue and white threads, which give them a slightly more interesting look than a plain poplin, where no weave it detectable. Similarly, twills will have a subtle diagonal weave and oxfords will have a rougher basketweave. Like how bolder patterns should be considered less formal than subtle patterns, the rougher texture of an oxford should be considered less formal than an end-on-end, which in turn should considered less formal than a smooth poplin. However, since we live in a seemingly never-ending “casual Friday” these days in America, all these fabrics are more or less acceptable in most offices. Which means if given a choice, I favor slightly more textured cloths when wearing solids rather than smoother plain weaves. 
To learn more about shirt patterns, consult these posts by Alexander West and Alex Kabbaz.

Patterned (and Textured) Shirts

As long time readers may know, I’m a graduate student in his mid-30s, and I teach and study at a research university located in the Bay Area, a region somewhat known for its casual culture. One way for me to dress down my usual sport coat and wool trousers ensembles is through patterned shirts. If solid blue shirts are a good alternative when white is too formal, then patterned shirts can make things more informal still.

There are two basic patterns for shirts – checks and stripes, with each having varying degrees of casualness. The rule of thumb is that the bigger or bolder the pattern, the more casual the shirt is considered. For example, madras and gingham are more casual than graph check or tattersall. Gingham is that “picnic table cloth” pattern you see here, and madras is the colorful Indian interpretation of Scottish plaids, which we’ve covered here. Graph checks and tattersalls, on the other hand, are a bit more conservative, with the first looking like … well … graph paper, and the second looking like two or three graph checks overlaid on top of each other. Gingham and madras should probably be reserved for weekends, whereas graph checks and tattersalls can be acceptable in more casual office environments. In the fall, I think they can look especially smart under “textured” sport coats, such as ones made from tweed or flannel.

Stripes follow similar principles. A hairline stripe, which you can see above, is when the stripes are so close together than they resolve to a solid when viewed from a distance. As I write this, I’m wearing a light blue hairline stripe shirt with taupe tropical wool trousers and a patch pocketed navy sport coat. On some level, perhaps a light blue candy stripe or Bengal stripe would have been better, since I’m also wearing loafers. That way, the casualness of a bolder stripe would match the casualness of the shoes. Candy stripes are usually about 1/8” in width, whereas Bengals are a bit wider at 1/4”. Those along with dress stripes (also known as pencil stripes) are the three patterns I wear the most.

Of course, I still think you should have a strong foundation of solid blue shirts. Depending on your lifestyle, those will probably be the easiest to wear. However, I will say that I only own two solid blue poplin shirts, and don’t plan to get any more. I’ve found that lacking a pattern, solid blues tend to be more interesting in something that’s not a simple plain weave. End-on-end and chambray, for example, have a nice criss-crossing mix of blue and white threads, which give them a slightly more interesting look than a plain poplin, where no weave it detectable. Similarly, twills will have a subtle diagonal weave and oxfords will have a rougher basketweave. Like how bolder patterns should be considered less formal than subtle patterns, the rougher texture of an oxford should be considered less formal than an end-on-end, which in turn should considered less formal than a smooth poplin. However, since we live in a seemingly never-ending “casual Friday” these days in America, all these fabrics are more or less acceptable in most offices. Which means if given a choice, I favor slightly more textured cloths when wearing solids rather than smoother plain weaves. 

To learn more about shirt patterns, consult these posts by Alexander West and Alex Kabbaz.

Cool-Wearing Shirt Fabrics for Summer
Warmer temperatures call for open weave shirtings - those lightweight, airy fabrics that allow your skin to breathe and body heat escape. My favorite summer shirting is linen. It’s so gauzy and open that it allows you to feel every gentle breeze passing through, but it’s also quite prone to wrinkling. Personally, I find a lot of charm in that, but it’s not to everyone’s taste. Additionally, depending on the quality of the linen, you may find that new linen can feel a bit rough. You can trust, however, that it will soften considerably over time.
In addition to pure linen, there are all of its variations. Linen-cotton blends, for example, will give you some of the benefits of linen but look less messy. I also recently came across a pure cotton that’s woven to feel and look just like linen. You can find any of these - pure linen, linen-cotton blends, and pure cotton woven to feel like linen - from a variety of makers. Brooks Brothers, J. Crew, and Howard Yount are good starts. Brooks’ shirts are better in their slim to extra-slim fit cuts, depending on your size. For more affordable options, you can check Uniqlo (which you can shop at through Suddenlee) and TM Lewin. For higher-end models, browse the stock at Ledbury, Mr. Porter, and Barney’s. The latter two are holding sales right now, which means you can get particularly nice ones at a more affordable price. 
I’m also a fan of pure-cotton oxford cloth (the stuff used to make OCBDs), but not everyone thinks they’re well suited for summer. For example, Michael Anton, author of The Suit, has written that he thinks they’re too warm for high temperatures. On the other hand, Alex Kabbaz, arguably the best custom shirtmaker in America, has recommended them. Personally, I find that my OCDBs wear cooler than many of my other dress shirts, but you should try wearing some for yourself and seeing how you fare.   
For those who have shirts custom-made, I also recommend cotton-batiste, cotton voile, and chambray. The first two are rather popular in Southern Italy, where the weather can get quite warm, but they have the problem of often being too translucent. Fortunately, A Suitable Wardrobe has some cotton voile shirting that’s very wearable, as well as a very nice, fine chambray. I would heartily recommend either of those if you can afford them. If you’d like to find other sources, check with your shirtmaker. He or she should have some from a variety of makers such as Thomas Mason.
And last, but not least, there’s madras, which we’ve already talked about here.
Of course, being that the world of shirting is wide and varied, it’s best for you to always check for yourself whether a particular fabric is good for hot weather. One trick you can employ is holding the cloth up to the light. If the fabric is lightweight and you see a lot of light passing through, it’s more than likely perfect for summer. 
(Pictured above: Bolts of fine chambray shirting at A Suitable Wardrobe. Photo taken from StyleForum.)

Cool-Wearing Shirt Fabrics for Summer

Warmer temperatures call for open weave shirtings - those lightweight, airy fabrics that allow your skin to breathe and body heat escape. My favorite summer shirting is linen. It’s so gauzy and open that it allows you to feel every gentle breeze passing through, but it’s also quite prone to wrinkling. Personally, I find a lot of charm in that, but it’s not to everyone’s taste. Additionally, depending on the quality of the linen, you may find that new linen can feel a bit rough. You can trust, however, that it will soften considerably over time.

In addition to pure linen, there are all of its variations. Linen-cotton blends, for example, will give you some of the benefits of linen but look less messy. I also recently came across a pure cotton that’s woven to feel and look just like linen. You can find any of these - pure linen, linen-cotton blends, and pure cotton woven to feel like linen - from a variety of makers. Brooks BrothersJ. Crew, and Howard Yount are good starts. Brooks’ shirts are better in their slim to extra-slim fit cuts, depending on your size. For more affordable options, you can check Uniqlo (which you can shop at through Suddenlee) and TM Lewin. For higher-end models, browse the stock at Ledbury, Mr. Porter, and Barney’s. The latter two are holding sales right now, which means you can get particularly nice ones at a more affordable price. 

I’m also a fan of pure-cotton oxford cloth (the stuff used to make OCBDs), but not everyone thinks they’re well suited for summer. For example, Michael Anton, author of The Suithas written that he thinks they’re too warm for high temperatures. On the other hand, Alex Kabbaz, arguably the best custom shirtmaker in America, has recommended them. Personally, I find that my OCDBs wear cooler than many of my other dress shirts, but you should try wearing some for yourself and seeing how you fare.   

For those who have shirts custom-made, I also recommend cotton-batiste, cotton voile, and chambray. The first two are rather popular in Southern Italy, where the weather can get quite warm, but they have the problem of often being too translucent. Fortunately, A Suitable Wardrobe has some cotton voile shirting that’s very wearable, as well as a very nice, fine chambray. I would heartily recommend either of those if you can afford them. If you’d like to find other sources, check with your shirtmaker. He or she should have some from a variety of makers such as Thomas Mason.

And last, but not least, there’s madras, which we’ve already talked about here.

Of course, being that the world of shirting is wide and varied, it’s best for you to always check for yourself whether a particular fabric is good for hot weather. One trick you can employ is holding the cloth up to the light. If the fabric is lightweight and you see a lot of light passing through, it’s more than likely perfect for summer. 

(Pictured above: Bolts of fine chambray shirting at A Suitable Wardrobe. Photo taken from StyleForum.)