For pinkfreud if still available to re-post my previous question
225155 which I closed without realizing I should wait for a possible
answer, not just comments.  The question is whether, for a few weeks,
it would be safe to brush my nails with urethane while I wait to see
if they will grow out strong.  My "beauty shop" sold me a product
which I tried but which mostly peeled off...overnight.

Hi again, calamityjane!

Thank you very much for accepting my previous comment as an answer. I
am reposting my remark, and have added some new information that I
hope will be useful.

I emailed a friend who is a Certified Aesthetician and asked her about
your situation. She does *not* think urethane is a good idea (it can
be toxic). She recommends a product called Nutra Nail Power Gel Nail
Hardening System. I found it online here (near the bottom of the
page):
 
Cosmetic Mall
http://www.cosmeticmall.com/cosmeticmall/frame.asp?Mode=2&AID=1061417&PID=177778&SID=105735614940700541&CategoryID=42&BrandID=0&SubCategoryID=290&Page=3

I have not located specific data on the subject of applying urethane
to the fingernails. However, urethane is a substance that carries
warnings directing the user not to apply it to the skin. Here's a
typical warning statement:

"Acrylic Urethane Waterborne Varnish Hardness Enhancer... Eye
protection, gloves and suitable clothing must be worn to avoid contact
with skin and eyes... In case of skin contact, wash off quickly with
plenty of soap and water, remove contaminated clothing."

AllPro Corporation
http://www.allprocorp.com/techbuls/CoroTB/2450TB30560AcrWBHard.cfm

According to my friend, the aesthetician, fingernails can be very
porous after artificial nails have been removed, and some chemicals
may cause an allergic reaction with the skin under the nails,
resulting in the loss of the natural nail. She does not know for
certain that urethane will cause this kind of reaction, but she says
she can't rule it out, and in a case like this it is better to be safe
than sorry.

A bit more advice from my friend (I owe her a free lunch for all this
assistance!) After acrylic nails have been removed, you can expect
that your natural nails will be weak and soft, and this will continue
until your nails have reached their whole length, so that all of the
nail that was previously covered has grown out. This takes several
months. In the meantime, try to avoid doing things that will stress
your fingernails, and be sure to keep your nails well moisturized.
Once a day, soak your fingertips in warmed vitamin E oil or almond
oil, then massage the oil into your nails.  Occasional temporary use
of commercial nail-hardeners is OK, but try to keep your nails open to
the air as much as possible. If you want healthy nails, you've got to
let them breathe.

Search terms used:

"urethane" + "contact with skin"
"urethane" + "fingernails"
"soft fingernails"
"stronger fingernails"
"strengthen fingernails"
"acrylic nails" + "removed"

I hope this helps! 

Best wishes,
pinkfreud

Pinkfreud-ga, I used the product the aesthetician recommended.  It is
a good hardener.  Thank you.

I have found no information regarding the safety or efficacy of
urethane when used on the fingernails. I hope another Researcher will
be able to assist.

Pinkfreud - Customer support told me I had to re-post my question
because I had closed it without an answer if I wanted to give a
tip/rating.  I re-posted so I could do this; you did try to help and
you gave me the name of a product which an aesthetician had recommend.
 I have ordered the product.  My new question about alcohol and germs
which Wonko answered was also meant for you and I hope he makes it
right.  Thanks, calalmityjane-ga

Ah. Now I understand. Please forgive my cranial density. ;-)

I will take another run around the Web to see whether or not I can
find anything more for you, and I'll post an answer soon.

Thank you!

~pinkfreud

Thanks so much for the five-star rating and the tip!

Hope your nails will grow in nicely. 

~pinkfreud