How would Libertarians prevent sweatshops?

In a libertarian society, is it expected that unions would prevent sweatshops and other unsavory work conditions?

According to my Encyclopedia, “By the 1930s sweatshops had been severely restricted in the garment and other industries through federal and state legislation, especially minimum-wage and child-labor laws.” So here in the US it took gov’t action to end sweatshops.

Do libertarians believe that if the gov’t hadn’t passed laws to diminish sweatshops, eventually unions would have grown powerful enough to improve working conditions? Or is it believed some other market force would prevent sweatshops, eventually?

Where do libertarians associate themselves with unions? Libertarianism technically allows monopolist hierarchy and nothing would prevent discriminatory firing or blacklisting.

The first thing a Libertarian would ask would be, “What’s so bad about sweatshops?” The people working in sweatshops aren’t slaves. They’re there of their own volition. If they don’t like the hours, or the working conditions, or the pay scale in a particular shop, there is nothing preventing them from peddling their skills elsewhere.

I was only speculating; I know of no association between libertarians and unions.

Nothing prevents them from forming unions, either. Oops! Of course that’s not true – we all know how unions are treated in the third world. If we’re going to enshrine the right of owners to pursue they’re own self interest, we should recognize the right of workers to do the same (which often means :gasp!: forming unions).

No, the first thing they would ask is: “How can I open one of my own–and then undercut that bastard over at XYZ Slave Manufacturers?”