Question
Hello, I would like to know if it's necessary to seal stamped concrete? I hired someone to put stamped concrete and said that it's not necessary to seal the concrete, is this true? What is the purpose of sealing concrete? Also,is antique release agent water proof? What are the proper steps when adding stamp concrete? I would like to know so I am aware of what look for before they start pouring the concrete. There are so many things like antique release, color hardener, slip resistant additive etc. DO I really need all these things for the stamped concrete?

Answer
Stamped concrete is a simple process that has these basic steps:
1. Pour colored concrete
2. Float concrete and lightly trowel
Optional, add color hardener to some areas to create a mottled natural look
3. Allow concrete to partially harden
4. At the precise time when the concrete will support weight and take a stamp but is not so hard that stamp is ineffective, apply color hardener or antique release agents to the stamps or stamp areas and apply the stamp.
5. touch up areas as needed to fix stamping mistakes, edges, etc.
6. allow concrete to harden and clean up.
7. wash concrete after 12 hours
8. saw cut any control joints that were not troweled
9. wash concrete again
10. allow concrete to fully dry and then seal concrete
11. wait 48 hours before using the concrete for intended use
12. wait at least 5 days before driving on it if possible.

Yes you SHOULD seal the stamped concrete, it does the following things:
A. It slows the curing process and makes the stamped concrete more even and stronger
B. It keeps put water and pollutants
C. It helps slow down the weathering of the stamped concrete and helps it retain its color and form
D. It will help to inhibit erosion from water that expands and contracts in the microscopic pores causing damage (specially in temperate climates)

Slip resistant additives are to go into the sealant to make it safe in wet conditions. It is necessary in a pool deck.

IMPORTANT NOTE!!!
Stamped and sealed concrete is very slick and can be VERY HOT in many areas of the US. In the stamping and sealing you will be effectively closing up all the fine pores normally in standard concrete (like a plain sidewalk). This means there is very little air space in the surface between your foot and the concrete. Normal concrete is rough and therefore your foot only comes in contact with a small amount of concrete and the rest is cooled by air. But with stamped and sealed concrete there surfaces is very smooth and therefore the concrete, specially darker colors, really get hot and they are often so hot that bare feet can not stand them.
This is not an exaggeration and I have made this mistake in my work. I never do stamped concrete for pool decks as a result. I did one pool deck with tans, grays and browns to match a slate finish and the pool deck was literally so hot that no one could be on it without shoes, the client wears aqua socks and has extra pairs for is guests. Don't make this mistake too. I am not exaggerating!

best of luck

PS you might like my blog at
http://www.seanjmurphy.com
or my landscape website at
http://amenityarchitects.com

Also look at my colleagues site  
http://www.decorativeconcreteinstitute.com/

Good Luck,
Sean J Murphy, LA, ISA, LEED AP
Director of Design at
B+C Studio
http://www.bc-s.net