I know something of copyright issues, having worked for a number of years as a paralegal/researcher in trade mark and copyright law, and being a publisher of patterns myself. It is a complex subject that even experts can get bogged down in, and it's never quite as simple as just counting the number of years from publication (or creation) date.
Copyright law has been fairly standardized internationally, and Canada's Copyright Act is in line with other major international legislation.
Essentially copyright exists for the life of the author, the remainder of the calendar year in which the author dies, and for 50 years following that year. So regardless of the date of publication, if the author is known, you must work from the date of death. If the author is still alive, copyright subsists.
If the identity of the author is unknown (often the case with old patterns and craft publications), the copyright exists for whichever of the following ends earlier:
(a) the rest of the calendar year in which the work was published, and a period of 50 years after the end of that calendar year; or
(b) the rest of the calendar year in which the work was created, and a period of 75 years after the end of that calendar year.
If the identity of the author becomes known during either of these periods, then copyright reverts to the original author as noted above (i.e. 50 years after the end of the calendar year of his/her death).
The law for multiple authors is somewhat similar to the above, with copyright continuing until 50 years after the year of the death of the last known authors/makers of the work.
So, for example, if you have a book published in Australia in 1930 and the author's name is stated in the book, then you should, to be completely certain the work is in the public domain, attempt to find out when the author died (not impossible these days with online record-keeping). If the author died in, let's say, 1950, then copyright lapses 50 years after the beginning of 1951, or 2001.
If the author lived to be quite old, it's conceivable the work could still be in the public domain. It gets a little harder to be sure of public domain status if the author's date of death can't be confirmed. In that case, taking the Australian book example, if one assumes the author was at least an adult when it was written, say about 20 years old, i.e. born in about 1910, it is highly unlikely he/she would still be alive. However, it is likely he/she might have lived until the 1970's, 80's or 90s', in which case 50 years after the date of death would put the work squarely within the original author's copyright.
The reason this is important is that in some cases, copyright royalties or contracts are owned by the family or descendants of an author, and they continue to have the right to enforce the author's copyright.
I would say that generally you're probably fine with a work published prior to 1900, but not always, especially if the author is named in the work and happened to have lived a long life. The only works that can truly and without doubt be said to be within the public domain that have known authorship are those published beyond the conceivable remaining lifespan of an adult, plus 51 years (working from the assumption that most books are published by adults over 20 years of age).
Of course people didn't generally live as long before about 1950, so to meet a 90-year-old was unusual in those days. If we take 90 years as the longest reasonable lifespan before 1950, and assume a remaining lifespan of 70 years from the earliest likely publication date, then add 51 years (after the year of death), that is 121 years from the date of publication, or (for the current date, 2015), works published prior to 1894.
So although many people believe the material they're using is in the public domain merely because it's "old", much of that material is still, strictly speaking, copyright. It's obviously easier to be on safe ground if the author is unknown to begin with and the work was either published 51 years ago (1964) or, if unpublished but without a known author, 76 years ago (1939).
I see items all the time being sold on eBay that I know are copyright, but whether the original owner/author or any royalty owners are interested in pursuing their rights through the courts is a matter of risk. Usually the higher the original value or popularity of the work (and the more recent), the more likely a violator is to be pursued. What irks me more is seeing eBay sellers who openly claim the item is "in the public domain", when in fact they probably have no idea whether this is true.
As far as use of a seller's own listing photos is concerned, this is of course the same issue of copyright. You can try reporting the matter to eBay and they may take down the offending listing on that basis, but not because of any copyright infringement.
Basically, once a work is truly in the public domain, if it is merely photocopied (in whole or part) and resold, then it remains in the public domain and is free to be used in whatever way a buyer chooses. Where an item in the public domain is converted into a new work (and there are varying definitions of what constitutes a "new" work, but generally that means some substantial addition to, or alteration of the original), then the maker of that new work holds copyright. This is the case with my own antique patterns, as they are over 100 years old, the authors are unknown, and they are almost completely reworked, revised, added to and altered by the time I publish them.
I apologize for the lengthy post, but I see so much misunderstanding of what "copyright" actually means (including confusing copyright with trade mark, a completely different thing), that I thought this might be helpful for others as well.
