Some have asked, so I will share how I starch my snowflakes, crocheted angels and other pieces... after trying umpteen different methods over the past 20 plus years this is my favorite...and it's cheap besides!
I use ordinary kitchen cornstarch, but there are commercially prepared 'fabric stiffeners' available. This is the method that I have been using for over 20 years now and my earliest pieces are still in excellent condition. It takes some time but is worth it!
Measure ½ cup of cold water into a large glass pyrex measuring cup.
Stir in 1 ½ teaspoons of cornstarch, ordinary kitchen cornstarch!
Microwave for 45 seconds, stir, and microwave again for 30 seconds, stir. May also be cooked on stove in small saucepan stirring constantly.
The cornstarch mixture will be SUPER HOT- be very careful!!
Toss the crochet piece into the cornstarch and press it down with a spoon and let it sit there to soak until it cools down enough to handle.
Once the cornstarch mixture has cooled down enough, take the crocheted piece out and gently squeeze out. The piece should remain fairly wet, but it shouldn't be drippy or gloppy. You can always repeat the starching (in fact I usually do at least twice) but if you leave too much starch on at the start it just makes a mess. It may take a few experiments before you come up with the right amount of starch to leave on. I have found that it is much better to UNDER-starch, then if the piece isn't as stiff as you would like after it dries just repeat the process. If you over-starch, often the only remedy is to try to wash it all out and start over.
Carefully pull the piece over your form or lay flat on a plastic or wax paper covered padded surface (I use a styrofoam board from the dollar store) smoothing into shape.
Pin with rustproof pins. PLEASE make sure you use RUST-PROOF pins!!! I learned that the hard way and it is very discouraging to find rust marks on your beautiful pieces! It is SO worth it to invest in a package of good rust-proof pins, trust me on this!
Let piece dry completely. I often place mine in front of a fan to speed the process, but expect this to take a day or so. Don't try to rush this, it's only dry when it's dry!
When piece is dry, if it does not seem stiff enough, I just make another small batch of starch and gently 'paint' the starch on my pieces with a small foam brush. This also works as a refresher to any other method you have tried that hasn't worked quite how you wanted.
I have been using this starch for years, and the earliest pieces done (like the little angel below which is about 25 years old now!) are still holding their shape extremely well with no yellowing occurring.
I have not ever experienced dulling with the cornstarch either, unless I mistakenly put too much on... years ago I used a cooked sugar water solution which I think does perhaps give a bit more shine but it takes longer to dry...
If you desire to investigate other starching methods, there's a lot of great information on both the 'Snowflakes and Thread Crochet' and the 'Crochet Memories' websites.