How would you solve this problem?

I don't use fish filler anymore, but did years ago and made my own.I used fine sawdust and plaster of Paris in various combinations to suit the job. Could still use it today if I was mounting using your half/cast method. Probably would paint Elmer's Wood Glue to the show side before filling to help adhesion if that was a problem. Back then I would dampen the sawdust and add the plaster as I was filling the fish. That way I could control the set up time. Worked for me back then since styrofoam wasn't invented yet. Today I would try mixing some thinned down Elmer's Glue with the sawdust instead of the plaster.Experiment with some of this, it might replace your current filler. Just a thought. Good luck, JL

 

I would probably remove head and tail or all fins and inject with any form of adhesive or glue that gets pretty hard when set and has some body to it or even a two part epoxy, or maybe silicone. Doesn't water hasten the set time of silicone? Can you use that to your advantage somehow?

 

A picture here is worth a thousand words Cecil! How you approach things might be determined on how bad the drumming is and the location. Once, I had a lake trout (I think it was) that had a small indent/drumming area near the tail after it dried where it wasn't snug to the form. Granted, your fish sounds like there's no material behind there so the situation might be different, but maybe not if it's only an 1/8" deep. Anyway, I took my customer's laker up to DougP's shop to ask his opinion. He looked at me and smiled, grabbed a propane torch and gently waived the heat back and forth around the area. The surrounding area must've expanded and contracted I'm guessing and the skin tightened up right around the area like magic! You would never know it even had an issue! This being said, obviously you could also very easily melt some of the foam underneath or crisp up some scales and create a bigger problem! But, dang - I was REALLY impressed, and have always been with Doug's knowledge of how to fix most any fish issues!

 

I'd try something that sets, like thin drywall compound durabond 20 perhaps, thru a good size syringe

 

I inject wallpaper adhesive into bird wings through a syringe. That may work for what your looking to do.

 

Cecil
I add powdered glue to my mix,
haven't used TS filler for other reasons
CL

 

It seems to me I remember you saying that you remove the fish from the bed prior to it drying so you can create a bend in the body, this may cause the separation your having, I create the bend in the bed and let the fish stay there till dry, I don't remember ever having a separation problem with TS.

 

try some low rise great stuff

 

Cecil Ive used caulk many times om fish that I have dented with my hard hands and these were even on competition fish. It takes about two weeks to set up but works fine

 

I would not inject something water based like wall paper paste or drywall compound because it will soften the skin back up. That could cause lifted scales etc.
I would drill out the vent area as much as possible, get a dollar turkey baster from the Dollar General and use thinned bondo to fill in the gap. Make it thin enough to flow between the skin and fish filler body. Just position the fish on amounting stand, vent up and pour the resin into the turkey baster to act as a funnel. If it's not flowing as good as you want you could put the bulb on with a small hold cut in it and use a blow nozzle from your compressor to provide a little more pressure. You might want to have a hose clamp ready that you can put around the base of the bulb. I have never had to do that but am confident it would work. What could possibly go wrong.

 

Cecil.

I have used a 20cc syringe with a 16g 1.5" needle to inject caulk into the places that drum on my fish. been using this technique for 7 years without any problems..... Also if I have a belly that I need to enlarge for eggs I inject caulk into the vent with one of the syringes I get from Second to Nature that has the curved tip.

 

It works!! I did this yesterday after seeing this post and about dropped the fish I was so happy!
Have to be very careful too! Thanks for this!