I have used Minwax Wipe-On Polyurethane on several pieces and like the results.  However, there is a residual smell that does not disappear for several weeks and if it is enclosed, for months.  The last piece was a large, openshelf bookcase.  The wood was long-leaf pine that I had recovered from a 100 year old house.  I applied two coats with 3 -4 hours between coats, waited overnight, and then applied 1 coat of clear and finished with one coat of satin for a total of four coats.  I brushed on the first two coats, sanded with 400 grit, and then wiped on the last two coats with a Viva paper towel, a technique I learned from FW.  The backing is masonite with a faux finish using gesso for texture, arcylic artist paint for color, and water based gel stain for the patina.  Ithought it would be wise to seal this backing, and I used nearly a pint of satin wipe on poly on the masonite because it acted like a sponge.  The end result is a nice piece but one that has such an odor that it is making my wife ill.  I am faced with removing it from the house.  I have several questions. 

1.  Why does this product have such a lingering smell?

2.  If I used fast dry varnish (Sherman Williams)  (not polyurethane) and low order mineral spirits as discussed in the FW Article, would it have a the same resulting smell or is the chemistry different?  I have used this technique before with good results after 6 coats.

3.  Is there anyway to seal the backing that has been coated in a pint of poly with another product such as shellac that would seal in the odor?

Basically, this is a chemistry problem regarding off gasing of wipe on polyurethane. This has become a serious problem.  Thanks.  ED