As mentioned in a previous post, handmade klaf has many hidurim that are not found in machine made klaf and is therefore halachicly preferable.
There are additional hidurim that might be available (at additional cost) from some klaf-makers. One such hidur, based on the opinion of the Chayei Adam, is that the hair-side of the klaf cannot be scraped at all during the tanning process. According to this opinion, scraping the back of the klaf – even if only a thin layer of the skin is removed – will negate its status as klaf which will invalidate it for use in STAM.
note: Klaf which adheres to the chumra of the Chayei Adam is called “litza” or sometimes just lo megurad (not scraped).
Many Poskim disagree with this position of the Chayei Adam. They maintain that the skin has the status of klaf even if the back is scraped a little bit, as long as the scraping is only done to smooth out the surface and remove the hair. However, if the back of the klaf is aggressively scraped to significantly reduce the thickness of the skin, it could be a problem according to other opinions as well.
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