Replies

1. 
   SamT | Jul 07, 2004 10:17pm | #1

   For chamfering the corners (a fillet in the form) we always used 3/4" chamfer strip, basically, a 3/4 x 3/4 square rod ripped on the diagonal into 2 chamfer strips. Tack it in place with 1" blue nails.

   For minor holes in the forms, depends on the final finish. If a smooth parged finish is desired, leave the holes, then stone off any bumps when the forms are stripped. If appearance isn't an issue, duct tape over the holes.

   Don't duct tape if appearance counts as it leaves large slightly depressed areas that are hard to fill evenly and if a little corner of the tape lifts (happens often) it will get stuck in the 'crete and be a bear to clean out and finish.

   If you want a real smooth finish like a countertop, you will want to make your forms perfect before the pour. Use Bondo, automotive lacquer and carnuba wax.

   If the holes are too big for tape, use aluminum flashing.

   SamT

   Arguing with a Breaktimer is like mud-wrestling a pig -- Sooner or later you find out the pig loves it. Andy Engel

1. 
   901Hal | Jul 08, 2004 12:26am | #3

   Thanks for suggestions. I'm not after the best "countertop" results, but close to it, and quite a few notches above large bulk pours where I have seen the 3/4" chamfer strips used. And yes, from my experience, the duct tape leaves just enough of an indentation to be noticable. I may explore the bondo and wax route; I don't think I'll need the hard coat. The fillets I am trying to achieve are about the size I get when I smear the caulk in the corners with my finger. It's just that I have had problems with the caulk 'blending' with the concrete.

1. 
   Gabe | Jul 08, 2004 02:40am | #4

   Cover your forms with a fresh layer of masonnite, glossy side out.

   Gabe

1. 
   timkline | Jul 08, 2004 04:09pm | #6

   masonite.

   are you serious ?  haven't you had any problems with the masonite buckling when it gets wet from the concrete ?  we have used 1/4" birch ply in the past.

   carpenter in transition

1. 
   Gabe | Jul 09, 2004 12:24am | #7

   As a facing for regular forms it has always been stable, moving with the plywood forms and has never buckled. It leaves a glass like finish on the concrete surface and is replaced after each use.

   Gabe

2. 
   Piffin | Jul 09, 2004 12:38am | #8

   Could be the difference between tempered and untempered, oiled or not. 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

3. 
   Gabe | Jul 09, 2004 12:57am | #9

   Not familiar with untempered and we do use a release agent.

   Tried heavy gauge poly but wrinkles/folds were everywhere. New formply leaves a nice finish but no sheen.

   Gabe

2. 
   arjmjk | Jul 08, 2004 03:06pm | #5

   Try using a smaller chamfer strip like 1/4 x 1/4 or some other type of molding.

2. 
   arjmjk | Jul 07, 2004 10:19pm | #2

   For the fillet, you can purchase a tri-angular cross-section piece of wood at the lumber yard and just nail it inside your form at the point where you want your fillet. Strike a chalk line and nail with small finish nails on the line.

   Regarding caulk, you should not have holes in your forms big enough to require anything like this--if this concerns you, your concrete is too wet.