Learn Polish: Skoro przędza to czysty jedwab, ta nić będzie bardzo droga. - Since the yarn is pure silk, this thread will be very expensive.

Toteż introduces a logical consequence, but it connects two independent clauses rather than starting a conditional one. You must state the cause first, then use toteż, followed by the result. You would drop skoro and say: Przędza to czysty jedwab, toteż ta nić będzie bardzo droga.

Why do we use to instead of jest in the phrase przędza to czysty jedwab, and how does it affect the grammar?

Using to is a very common and natural way to equate two nouns in Polish. When you use to, both nouns stay in the basic nominative case. If you used jest instead, the second noun phrase would have to change to the instrumental case: przędza jest czystym jedwabiem.

The noun nić ends in a consonant. Why does it use the feminine words ta and droga?

While most Polish nouns ending in a consonant are masculine, nić is an exception. It belongs to a group of feminine nouns that end in a soft consonant, similar to noc (night) or miłość (love). Because it is a feminine noun, any adjectives or pronouns describing it must take feminine endings.

What is the exact difference in feeling between using skoro (since) and ponieważ (because) here?