Gluing a hairline crack

[smart dog]

Hi Folks,
Can anyone suggest a good method to repair a hairline crack in a gunstock?  I cannot open up the crack to insert glue and need something to dribble into the crack.  Can AcraGlas or CA glues be thinned to aid flow into tight cracks?

dave

[sz]

Ues acra-glas (not the gel)
If you warm it a bit with a hair drier is get as thin as oil.

Blow it into the crack with canned air (like what you blow out computers with)
Clean off the mess with rubbing alcohol on a piece of cloth

[E.vonAschwege]

Alternatively, buy a small bottle of "Hot stuff" CA glue, it's thinner than water and has no surface tension, so it goes EVERYWHERE.  It will wick well into a crack and solidify - I put it on the tip of an x-acto blade and apply it with that.  If gluing a small splinter, buy some activator spray to make it bond instantly (well, more instantly than it does already).  If the crack has occurred while building, if you're careful when you apply the glue, it will be invisible when you take the wood down to final depth.  Good luck,
-Eric

[smylee grouch]

Is the stock stain ed and finnished? I have in the past had some trouble getting stain to penitrate in unfinnished maple.

[smart dog]

Thanks Guys,
The stock is finished but the crack coincides exactly with a grain feature so even a dark line is invisible as it mimics the grain. I think I will try Eric's idea. I will refinish the spot and it should match perfectly with the crack essentially gone.  It is walnut with no stain so matching color is no problem.

dave

[T*O*F]

You can thin Acraglas with lacquer thinner as necessary.  I do it all the time to flow it down into cracks.
I never had any luck with any of the super glues, though I've tried several times.

[frogwalking]

If you can find a place to drill a hole, intercepting the crack from a different direction, you can inject glue (CA or thinned accruglass) under pressure using a dental or glue syringe.  We used to grout cracks n rocks and concrete using a version of this method.  I once used it to glue a crack in an (unmentionable) gunstock.

[FALout]

Use some masking tape to protect the area around the crack whether or not the stock is finished, any excess glue can cause problems.

[Captchee]

  As Eric alluded. Thin CA , would be the way to go .
 Now there is a difference . Super glue or what sold in   stores like Wal-Mart Home depot  … is not quality CA glue and its most times either medium or thick .
What your after is a quality , fresh , Thin ,CA glue .  IE CA come in 3 grades .
Thick  or gap filling .
Medium 
Thin . Which is so thin that’s near the level of a penetrating fluid . It will go places that water wont , even to the point that it will run down the threads of a threaded bolt or screw .
All 3 grades are made for  plastic , foam  or wood  and whats called a kicker for  type . What the kicker does is instantly cook off the glue .  Done breath the smoke .

 Believe it or not I have found  hobby stores that sell RC  equipment have the best prices . The normally sell a lot so the glue is fresh . They also normally have more then a few brand names to include their own .
 The bottle also come with a small drip tip .
Ie would do just what Eric mentioned .  Get the thin. Put a couple drops on the end grain  you should quickly see it  down towards the bottom of the crack . It wont take much . Let it set . While it maybe dry on the outside in a couple seconds , the inside takes alittle longer . Maybe 5 to 10 minutes to be on the safe side  .

[EC121]

Towerhobbies.com has more glue than you will ever use.  I think they even have super thin.  Cheap shipping on small items.

[Mark Elliott]

I am with Eric all the way on this.   I use the exact same Hot Stuff CA.   You can buy various thicknesses at WoodCraft.   The original one is very thin and will get sucked right into a thin crack.   It is my primary method for fixing the type of crack you described.

[D. Taylor Sapergia]

CA works wonders in a crack.  But on unfinished maple, the cured stuff may interfere with any stain you want to apply later.  So keep that in mind.  Perfect for walnut.

I build myself an English warbow - 100 + pounds pull at 32"  - from a questionable piece of Pacific yew.  The stave had a lot of drying checks that appeared to run all the way into the heartwood in places.  So after roughing out the bow, I applied thin CA to all of the cracks.  As the stuff cured, I continued to apply the glue until I had a build up on the surface of the wood.  Finally, I cut it all away down to the wood, and the CA completely filled and 'cured' the cracks.  The bow is a complete success, from an otherwise un-usable stave.  The point is Cyanoacrylate (CA) is amazing glue.

[WadePatton]

I knew a luthier once, back before i cared about wood-working, and spent some time in his shop.  He used a lot of CA, mostly thinned out versions or with a thinner to get penetration.

[bob in the woods]

I always have "Hot Stuff" in my shop. I use it for crack repair, fixing defects in Brazilian RW [ the norm now ] and for bindings /purfling etc.  It is wonderful stuff.  Be careful re using the  accelerator , since if the humidity is high, the quick cure will turn a frosty white. 

[Dave R]

When using CA glue be sure to remove all metal around the area you glue, How do I know? I once glued a split ramrod groove in a fore stock and I thought I would never get the barrel out!! CA will glue just about anything that it flows to!!

[E.vonAschwege]

Just as a general FYI for members:  While "krazy glue" and other brands from the grocery store technically are CA glue, they've usually been sitting for a long time and just don't have the oomph that good hobby CA glue does.  Fresh CA glue is best, and stays better for longer if kept in a fridge.  The one exception I've found is "Gorilla" brand super glue, which is very thick and not good for hairline cracks, but good for when you don't want the stuff to run everywhere. 
-Eric

[Marcruger]

I will preface this by saying I am no expert.  I have done a bit of guitar work in my time, and ran a music shop for a year.  Guitar wood repair has a lot of parallels to wood repairs on rifles. 

One caution with CA glue......it can really "haze" an existing finish, and turn it milky looking.  I believe the fumes can do it as well as the glue itself.  Of course, that may just be the finishes I worked around, and not longrifle finishes.  Test before proceeding. 

A trick I learned to fix a crack was (if you can get to the end grain or end of crack) is drill with a pin-vise and jeweler's drill a tiny bore hole along the center of the crack.  I would then basically fill the tiny bore with "Zap-A-Gap" gap-fill super glue.  That stuff will bond anything to anything......except wax paper.  By filling the bore it wicked into both sides of the crack.  Makes for a sturdy repair.  Zap-A-Gap is used in hobby models and such, and bonds materials while filling any voids or gaps. 

Again, test it around the finish you are working near.  CA is some funny stuff. 

I have also corresponded with folks that use Hot Stuff inside the inletting of longrifles in high-stress areas to prevent cracks.  I am guessing it glues adjoining wood fibers together much like plywood. 

Keep in mind that Super Glue CA does not age well, and sometimes makes a slow-curing mess if it gets too old.  On anything I care about, I always crack open a new bottle. 

My one last thought would be that I would try to use superglue AFTER staining, but BEFORE finishing.  That way stain could still get in, but a final finish would not get hazed or milky. 

God Bless,   Marc

[EC121]

The fumes from CA will haze the plastic covering on a model, but acetone will usually get it off.  The acetone removing the haze would also probably take the finish off a rifle. 

[ShutEyeHunter]

I've used a bunch of adhesives to fill cracks. For me, the trick to getting the glued area to blend in is to seal the surrounding area first with shellac.  Zinnser has a clear & dewaxed in a spray can that's available at home,depot. You can spritz a bit of it into a bottle cap and thin with a drop of denatured alcohol,to get precise coverage with an artists brush

I use that as a sanding sealer over the whole stock, so the repair doesn't stand out if I if do a small area.

Then again, I use only alcohol based stains

Scraping after the repair with a double edged razor blade will give you a smooth finish... Watch your fingers...

[smart dog]

Thanks everyone,
I ordered some Hot Stuff CA glue (thin, and gap filling) and will store it in the fridge.  The thin glue should do the trick.  I also have a very abused Pedersoli Brown Bess that I am refinishing for a friend.  It is an early production from Pedersoli when they did a good job on the stock details so it is worth restoring the stock.  It has several thin cracks in areas where the finish is badly worn from getting wet and drying out.  I'll try fixing those with the CA glue as well.  Thanks again.

dave