Clean always sells better....because with old textiles, there is always the question..."will it fall apart if I wash it."

Next is the matter of "what is old?'...1940? 1930? or 1890 or older??
Stuff from the 1940's in good condition, without colored embroidery, should do well soaked in oxyclean and just squeezed out (not wrung!) and laid out to dry.

Older things or more delicate...hand done lace, gauzy fabrics are best soaked in a non ionic soap...like Orvis...look at a quilt shop.
then remember that wet fabric is weak....so don't lift it by an edge, support it with your hands...soap residue weakens fabric....rinse well but very gently, and anything acedic..like cardboard weakens and yellows the fabric.

So if you have some really old and nice things....soak in a plastic tub (like those storage containers) with distilled water and orvis....soak until the stains are gone....2, 3, 4 or more days. Squeeze our and replace with more distilled water..., gently press down into the water to rinse...repeat, several times until, with litmus paper, the water tests neutral.
Carefully lay out to dry in front of an electric fan....keep the cat off your drying linens!!!

Some of these things, like the collars and cuffs, I would guess are from the late 1800s or very early 1900s. Others are perhaps 1920-1930 when my grandparents were setting up their home. I just came across a piece that looks like part of a blouse that one might wear under a jacket (kind of like the dickeys of some years ago only it comes down to the waist and is very lacy and feminine). It definitely never had sleeves. It's a very thin cotton, not linen. I'm familiar with Orvus soap, but where can I purchase litmus paper?

should be able to find litmus paper at a pharmacy...or on line.

That lacy thing is called a jabot. Look closely for hand made lace and hand loomed fabric. I would love to help you sort that stuff!!!!

Thanks Linda...your answer is basically the same as my very novice one and I learned something too! Orvus (Orvis?) can be found easily in feed stores...as horse care (I have been told) product. But it works well. Distilled water I had never considered. I have washed many antique doll clothes where the fabric was fragile in the first place with good results. Have never had to, but have been told that you can soak those yellowed items for very extended times. No patience here, so that hasn't happened.

Don't laugh, but if, after removing stains, the linens are still yellow, would a little bluing in the final rinse be ok? Since I started using bluing on whites I have beautiful snowy white towels, t-shirts, lingerie, etc. Even old yellow t-shirts look bright again. I swear by the stuff.

Blueing helps....and remember...in a pinch you can use blue food coloring!

I haven seen blueing in years.....I remember loving it as a kid...I would be allowed to swish the blueing bag in the rinse water....what fun! Mrs' Stewart's Blueing!

Yes, Linda, it's Mrs Stewarts! Great stuff, available right next to all the other laundry products in my stores. Plus, there is a website.

Let me recommend this cleaner, you can read all the comments about it

Here is a link that might be useful: Linen cleaner

Pieces like cuffs, collars, and ruffles may have been starched and ironed. For pieces that are starched, the cleaning product will have to contend with the starch. Starched pieces loose their stiffness and sheen after laundering. The pieces may need starching again to recover stiffness. I'd be hesitant about ironing really old cloth.

The natural color of early linens were not snow white.

Closely examine the lace trims for hand made bobbin lace. The repeating pattern of machine made lace will be very regular and consistent; Hand made lace, on the other hand, may show minor variations in the repeated pattern. (My daughter does bobbin lace at Ren fairs.) Hand made lace may date the piece to an early date.

Starch is water soluble and washes out very easily. But linen doesn't need starching, it is a thermo plastic fiber that stiffens naturally when ironed. But iron carefully. Rinse well before ironing as soap residue scorches....and have the pieces very wet when ironing.
And you may find hand made bobbin lace as well as needle lace on old linens....and on new ones too...if they are high end!

I am definitely seeing hand-made lace on some of the items. Haven't had time to start to clean them yet, though, but I appreciate the recommendations. I will order some litmus strips online (100 for $2.00 at Edmund's Scientific). Most recently I came across a hand stitched patchwork quilt. Haven't unfolded it yet, but it looks surprisingly clean considering where it's been stored for at least 60 years.

Take pictures....for those of us who want to enjoy your find vicariously!

Linen is made from the fibers of the flax plant. It is not a thermplastic. For example, nylon and rayon are thermoplactics. Phenolic and melamine are thermoset plastics.

Jem...I suspect you have never ironed a linen napkin. When a very damp linen napkin is ironed with a hot iron, it becomes stiff as if starched and very glossy. If linen is hard creased with a hot iron, it can be almost impossible to remove that crease....it remains even after washing and ironing several times. Thermoplastic means that it becomes more "plastic" with heat....able to have creases heat set. Linen is able to do that.
I iron linen napkins, wet from the washer with a very hot "non-steam" iron and hang over a dowel until completely dry. Then I go over them again quickly with an iron, and fold to store. They look and feel starched, stiff and shiny
Else where you may read that chlorine bleach yellows linen...not true...but it will weaken the fibers.

Lindac:

I'm sorry about that. My technical side popped up to have a say, and it isn't very diplomatic. I do agree with you that several frabics, linen in particular, will take a set and hold creases and flat shiny surfaces if dampened and ironed. When my mother laundered her crocheted doilies, she heavily starched those to make the ruffles stand up and the piece to hold its shape. Back when she made those, she used cotton cord/thread. (I had to request her not to starch my hankies, starch only the ones that were to be placed in a suit jacket breast pocket.) And yes, I have ironed a few articles of my own clothing. I avoid it as much as I can [smile].

The use of the term, thermoplastic, has a very specific definition in the business I was in (as applied to materials). I have designed many molded parts in both thermplastic and thermset plastics for a living.

I should have said "thermoplastic"....

I'm a big fan of Orvus. You can use it to soak your antique linens, and you can use it to wash your horse. I purchased a big tub of it at the feed store.

Don't forget about the magic of sunshine. After a good several-day soaking, followed by a thorough and gentle rinse, lay the items out on the grass (on a sunny day). That will take care of many remaining spots. Really amazing! I think colors might fade, but it sure works on white and ecru. I don't think there is a risk of your horse fading.

I wanted to echo what Hounds just said about laying out on the grass. Works REALLY well! (I had to borrow my neighbor's lawn last time I laundered antique linens, but they were beautiful!)

Yep....sunshine works wonders....and also damages fabric. Ever seen drapery lining that has "gone to pieces" in a south window. I also have seen curtains that fell apart on the pleats.
But I'm not saying that an afternoon in the sunshine would do that. We used to have a closely trimmed hedge that would support a napkin with a stain, without the danger of the dog walking on it.

Thanks for all the great tips. I am inundated with stuff to clear out of the house, but will try to post pictures of the interesting stuff, including the quilt.