Laundry was probably the household task most detested by the Civil War Era housewife.
One 19th century diarist, Rachel Haskell, called it "the great domestic dread".
It was a time consuming, often days-long process.
Washing a "good" dress might being with the laundress removing the trimming and the buttons. Then she might separate the lining from the garment itself to keep the weight of the wet fabric from stretching unevenly. A day dress might have five yards of fabric in the skirt alone! Then the washing process could begin.
Clothing would be soaked at length (perhaps even overnight), then scrubbed on a washboard with lye or vegetable soap.
Next, the clothing would be placed in a vat of boiling water and stirred with a long stick to prevent yellow spots from forming. Of course, not all dyes were colorfast, so the garment may lose color in this process.
The clothing would be rinsed again, perhaps with a bluing agent, to increase brightness and whiteness, and then wrung out (a process demanding considerable strength!) and hung to dry. During the winter, the clothing would have to be hung indoors, in a room with a fire, and the process could take days.
When the clothes are still damp, they would be taken off the line and ironed with heavy flat irons and possibly starch.
Then, our exhausted housewife would have to reattach lining, buttons and trims, so the dress could be worn again.
This is why chemises, petticoats, pantalets, aprons, undersleeves, and detachable collars were so important in protecting the main outer garment from soil -- they were much more easily washed. The casual observer assumes those items exist for modesty's sake, but it is really for practical's sake! It is also an excellent reason to incorporate these items into your impression - so you can explain their purpose to spectators.
