That is the kind of print job that rarely requires exact matching.

If you have actual need to get a match, you will need to use a reference system like Pantone. Think along the lines of a major corporate logo. It should have been a part of the bid.

For most tshirt orders you will need to trust the person working on the other end. Ask them for their thoughts and listen to their response. They spend all day, every day working with the materials and know how yours will look.

You won't get a perfect color match from the image, but you can check everything else. Tell them your concerns and ask them questions before you sign off. If they are hesitant about your design it is a big warning. If they are confident it will look nice, go for it.

It depends. Something like a corporate logo that it supposed to be exactly a specific reference color needs to match exactly. Something less precise like a family reunion banner would have more leeway. The clients, the job details, and the nature of the job tell a lot even without explicitly asking.

> How does a graphic designer work with colors in Photoshop, knowing that many colors can't be accurately represented in RGB on their computer monitor?

First off, Photoshop itself has some tools. You can configure your color spaces while working. Photoshop will then highlight unprintable colors when they're out of gamut. It can also highlight colors that will exist in print but can't be displayed on your monitor.

Other than that, print shops use boxes and books full of printed color reference cards.

If you aren't color matching a reference system like Pantone but are instead trying to see exactly how the final print will look, shops will print out a bunch of their own reference cards and chips on the papers, cardstock, vinyl, polyester, or whatever it is they'll be printing on.

And it isn't enough to just have one and keep it forever. Papers fade and discolor, inks fade and discolor, so the colors can drift away in unacceptable ways after two or three years. Bigger print studios will budget a few thousand dollars each year to continuously update their reference colors.

Every blend ends up being slightly different. Printing a specific CYMK on one brand of cardstock will have different appearance than that same CYMK on a different brand of cardstock. Printing on glossy paper will look different from matte paper. Printing on paper versus printing on vinyl will look different. Each one will be similar, and some will be nearly identical, but visually each will still be different.

That's part of the appeal of Pantone, the print shop is supposed to account for it and fine tune for whatever inks, dyes, and media they're using so it produces a match. If someone is expecting P15-5519, but it happens that the specific paper happens to make the print a slightly greener turquoise, the shop is supposed to adjust the color mix so it matches the reference color instead of matching a specific CYMK blend. If this combination happens to need a little more black or a little less yellow, they'll adjust the CYMK to whatever it needs to be in order to visually produce the Pantone color P15-5519.

Getting the colors to match exactly is one of the reasons for proofs before a big print run, you want to verify with the customer that they're satisfied before running the full batch. It isn't just for issues like spelling and placement (although those are part of it), it's also to ensure the color is precisely what they expect on the various media used.

There are 3 other replies, but I don't think any are really ELI5.

The answer needs a few parts:

> What exactly is keto?

Keto is short for ketosis, a change in how your body uses energy.

Your body uses building blocks for all kinds of things. Two of those building blocks are carbohydrates also called sugars, and hydrocarbons also called fats and oils. The body uses them for many purposes including using them to make energy. In chemistry the difference is fairly small, carbohydrates (sugars) contain Carbon, Hydrogen, and Oxygen, and hydrocarbons (fats/oils) contain Carbon and Hydrogen. The body is able to burn both of them for energy but it takes a slightly different chemical reaction.

Normally the body likes to use sugar (carbohydrates) found in food. If you don't eat enough carbohydrates, your body switches over to use fats and oils found in food. It takes several days of not eating carbohydrates before your body decides it needs to switch gears and get most of its energy from the fats and oils in food instead.

Normally when your body uses sugar it converts it into energy, water, and carbon dioxide.

When your body is in ketosis, the process of using fats and oils generates energy, water, and carbon dioxide, but the different chemical reaction also produces some acids called "ketones". That's where "keto" and "ketosis" get their names.

More on this in the third part.

> What is acidosis?

Acidosis is when there is too much acid in your blood.

There is an acid/base balance in your blood. Normally your blood has a pH of about 7.4. If your blood becomes too acidic it is called acidosis. If your blood becomes to basic it is called alkalosis. Acidosis is when your blood pH drops below about 7.35. Alkalosis is when your blood pH goes above 7.45.

Both acidosis and alkalosis are bad for your organs. If the blood is too acidic or too basic, your organs will start to fail and you will die.

> What is keto-acidosis?

It is acidosis (blood turning acidic) caused by ketosis (using fats and oils).

Burning fats and oils is a normal thing for your body, and it can usually handle it just fine. Normally your body can neutralize the acids and extract it into urine just fine. Sometimes, your body can't keep up. Diabetics are much more likely to both produce more ketones and also have more difficulty filtering them out.

If your body can't process the ketones out fast enough your blood becomes acidic.

When that happens, your body quickly shuts down. It depends on how acidic your blood becomes and how quickly it is shifting, but for many people ketoacidosis will kill in less than a day. The damage the acid does to your body can be reversed if caught quickly enough, but if doctors can't fix the acid-base balance in your blood quickly enough, you can get permanent damage in just a few hours, and then die.

> is it possible to unknowingly get into it..

Yes it is possible, but your body will feel really sick, really quickly. People feel super thirsty, start throwing up, have stomach pain, act confused, and smell weird like fruit. Usually people will recognize something is very wrong and will go to the hospital.

Since people with diabetes are more likely to experience it, it's good to learn the signs if you are around diabetics.

It is easily treated at the hospital if it is caught in time.