I've been making water soluble decals by the process featured in Control Line World with a pretty good degree of success.  I do everything as recommended by Richard Oliver.  There has been some failure rate related to the exact technique for applying the Krylon Clear Coat, but I can deal with that.

My question is:
Exactly what is the water soluble adhesive used between the decal than and the throw-away paper backing?  Sometimes (actually all too often), this glue gets washed away around the edges and it would be nice to beef it up with some of the same stuff. 

Volitile stuff like dope and CA messes up the process and the underlaying finish. 

I'll take a shot at that.

When I first started this process, I tried to seal the decals with some other rattlle-can clear products and they didn't work.  The clear fused he decal to it's backing so firmly that it would never soak off.  On the recommended Krylon worked.  But I didn't try clear dope.  So I'll give that a shot. 

But I'm still looking for the actual glue that comes with the decal as a base plan.

Getting rid of the Krylon would be nice.  I like to finish a model in JUST ONE product for future repair work.

I don't shoot them with anything till they are in place on the airplane then shoot it with clear when I shoot the airplane.  I am real carefull with the first couple coats, too heavy and it will melt. You also have to be real carefull when applying but I usually make enough spares to be able to mess up a few.

I have been using Micro-Mark and other decal paper with pretty good success lately.  There are 4 basic types:  Clear or White in Laser or Inkjet.

Clear is fine if you have dark colors or are going over a white base.  White is better if you have light colors you need to put over a darker base.

Inkjet is great if you don't need to clearcoat the model and rub it out.  Otherwise you need to pre-coat it with a compatible clear-coat before application.  If I am doing a Butyrate finish, I use clear, non tautining in several misted coats to protect the ink, then apply it and apply the final clear to the model.  If it is on, say Monokote or Coverlite, I hit it with misted coats of Clear gloss or matte Lustercoat to build up a barrier, then apply it.

For finishes that will be clear coated, then rubbed out, I prefer the Laser material.  Clear vs White base is the same.  The advantage is that you can immediately apply the decal, and it is VERY thin.  When you clearcoat over it, the edges will dissapear.  For the ultimate pro finish, this is the ticket.

Now, how to do the Laser decals:  Since I don't have a laser printer (the ultimate!), I print my art on top quality photo paper at maximum quality.  Then I take it to Staples with my laser paper and copy it with their machine.  DO NOT go to Kinko's, as their machines run too hot and the paper will stick.

When applying I use a drop or two of dish detergent in a cup of water in a pie tin, wipe down the target surface with it and soak the decal in that water.  The decal will curl up like you won't believe.  Leave it!!!  Pull it out of the water and set it aside for several minutes until it relaxes.  Then it may be slid off without cracking.  

What is happening is that the paper base expands with the water, but the decal is rigid, thus the curl.  When the adhesive softens, the decal can slide a bit and the curl comes out.