softer fillers is better than hard fillers when it comes to models?

I have heard this said about CA's (superglues), but personally have not found it to be a problem, if it's even true. (Is it true?)  I always use CA's for fillers, sometimes letting them sit overnight, and have had no big issues sanding them down and leaving the plastic intact. 

For sanding, I don't have any paper coarser than 240 grit.  I also use finger nail emery boards like you can buy in the cosmetics section, then follow with sandpaper.  In most cases, I start out with 320 grit, then move to 400 and then to 600.  Usually this is all that's necessary

Lately, I only wait about an hour for superglue to dry, then sand.  It seems easier to work.  If it hasn't quite set in an hour, I wait a few minutes then try again.

Well Checkmate I guess this is why I brought this thread up.  I tried using the CAs as a filler to be worked down.  At that point I thought I was sanding more plastic away than CA.   Like you I was using a four sided nail board, nice but they don't seem to last very long.  I've been using the Testors filler, but seems to me to be messy (oils and fillers seem be separated) and had to be put on a pallet and mixed quickly then put where needed.  Plus the Testors seemed soft at times and very hard at others.  Usually this was before I learned to mix the filler.  I'm looking for the best filler, but I've this felling that different areas calls for different fillers.  Sorry about not following up any sooner than this.

Thanks for your input.  Bud   

With soft fillers you risk the other extreme, sanding filler below adjacent plastic.  Best if filler has about same hardness as plastic.  I use auto body glazing (spot) putty, close enough. I have had the reputed problems with both the "too soft" and "too hard" kinds.  Reminds me of Goldilocks :-)

I'll repeat what Don said- auto body putty is the ideal...  I got back into the hobby 3 years ago and basically started from scratch, I have tried CA as a filler, softer putties like Squadron as a filler, and finally found the perfect in-between in auto body filler...

The trouble with Ca filler is that is is too hard- it dries like concrete.

the trouble with "model putty" like Squadron is that it is too soft and also tends to have bubbles dried inside which reveal themselves as you sand- and then require more filling.

Auto body putty is the perfect in between.  It dries hard but can still be sanded.  The best I have found is a 3M product called Acryl-Blue.  I have never found it in an auto-parts store, only online.  However, 1 tube will last you forever.  Acryl-Blue thins with 90% alcohol, dries in about an hour and makes such a great filler that you will never look back!

I've been using the Testors filler, but seems to me to be messy (oils and fillers seem be separated) and had to be put on a pallet and mixed quickly then put where needed.

Testor's thins with rubbing alcohol...  I apply it either with the fingertip or a spreader made from a piece of scrap styrene... An alcohol-moistened finger will remove most of the excess, making sanding a light chore... Best used in concave areas like a wing/fuselage joint..  Knead the capped tube a bit before use and you won't have the separation issue...

I also use Bondo Red Gazing Putty, but it thins with Testor's Cement or MEK and will attack the plastic if you don't pay attention to it, since it's laquer-based... Best used on large, flat areas, convex areas, and atop fuselage seams...

As with ALL putties and fillers.. Wet-sand, wet-sand, wet-sand...

I generally use a softer filler like bondo red tube filler or squadron instead of ca glue for ease of removal and less chance of sanding away details.