It is a win win situation
Archival Picture Framing Mats
The stock answer is use archival mats and backing if your art has an actual or emotional value that makes you want to preserve it for many, many, many years.
Of course, the question is far more involved than simply the stock answer. It is true that value is a primary influence on your decision to use archival materials. However, there are design issues as well. Archival pulp mats have a very bright white core. This gives a really crisp, sharp appearance and works well with many prints. However, some prints require a more subtle appearance. The white core is distracting. You could use a creamy colored cotton rag. You could use black core or other color core. Or, you could use plain old standard core which is a bit creamier than archival core.
There are also marketing issues. Archival is more expensive. This is a problem if you cannot raise your prices to accommodate the increased material costs. On the other hand, $0.50 or $1.00 spent on a great archival mat or cotton rag mat can sometimes get you many times that in price. It is not how much you pay for the mat that matters. It is how much profit you make on the item you are selling. So, as usual, there are no stock answers. Just more questions to ponder.
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