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Building Tips and technical articles. => Building techniques => Topic started by: Lee Thiel on July 28, 2011, 08:06:40 PM

Title: No Sticky CA
Post by: Lee Thiel on July 28, 2011, 08:06:40 PM
Putting my carrier back together after a bad first flight attempt.  Using CA to patch some cracks, and it will not hold at all.  From what I can gather, the wood is to dry.  I tested lots of scrap balsa that I keep, and none of it will hold together either.  This is with 3 differents brands of CA purchase today, from different stores.  I dipped two 1/4 pieces of balsa into water, wiped them off on a rag, put them together, added a drop a CA, and they bonded fine.  Do you think a humidifer would help.  My build room is 10 x 12 and is kept at 75 degrees in the summer.  It stays dry year around.  I can spray paint in it, no matter what humidity may be, with no blush at all.  Suggestions are welcome.
Lee TGD
Title: Re: No Sticky CA
Post by: Peter Nevai on July 28, 2011, 09:26:21 PM
Some moisture is needed to kick off most CA glue. Also with CA less is more. A heavy application requires more moisture to set. Even gently blowing on a joint is sometimes kicks off the CA from the moisture in your breath. There are sprays that can be purchased that help CA set.
Title: Re: No Sticky CA
Post by: Wynn Robins on July 28, 2011, 10:13:01 PM
Some moisture is needed to kick off most CA glue. Also with CA less is more. A heavy application requires more moisture to set. Even gently blowing on a joint is sometimes kicks off the CA from the moisture in your breath. There are sprays that can be purchased that help CA set.

breathing on it is a good option if the wood is dry - DONT use a CA accelerator on dry wood or you will get fire.......ask me how I know.!!!!
Title: Re: No Sticky CA
Post by: Lee Thiel on July 29, 2011, 05:13:10 AM
 No way of knowing the age of the CA.  Three bottles were purchased yesterday, from different sources.  I suspect really dry wood is the problem. The wood I moistened bonded fine.
Thanks, Lee TGD
Title: Re: No Sticky CA
Post by: john e. holliday on July 29, 2011, 08:07:53 AM
Get a spray bottle and lightly spray the area.   And as Ty says, CA on old CA will not cure unless you put some baking soda in the joint.  I use wood glue or epoxy when doing joints on a rebuild.   H^^
Title: Re: No Sticky CA
Post by: FLOYD CARTER on July 29, 2011, 12:23:17 PM
Lee indicated he was doing a repair job.  CA works well on parts that are newly broken, but will not work over old glue!  It's always a good idea to have a tube of Ambroid on hand for joints that CA won't touch.

Floyd
Title: Re: No Sticky CA
Post by: Lee Thiel on July 29, 2011, 12:44:55 PM
Thanks for all the tips. H^^ Just have a few cracks that I wanted to CA.  Most everything else will be done with epoxy.  The baking soda thing is a new one for me.
Lee TGD
Title: Re: No Sticky CA
Post by: Steve Helmick on July 29, 2011, 03:20:58 PM
Bob and Billy Hunter, the guys that first brought CA ("Hot Stuff") to the average modeller, had the baking soda tip in their info packet. Their suggestion was to use a baby nose syringe to puff baking soda onto a CA wetted joint.

If I had a less than stellar part fitment, I would lick the balsa (end of rib or spar notch), then dip in baking soda, brush off all visible traces of baking soda (AKA "BS"!), assemble and put a drop of CA on the joint. Done deal.

One of the things I did a lot for scratch building FF's was make little jigs and fixtures to help cut identical parts or assemble parts accurately. A big glob of BS (baking soda!) works much like a blob of epoxy of similar size, but cheaper and much quicker.  #^ Steve