Would like advice, bedding/air bubbles

[oldred]

I am going to be bedding another rifle stock in the next couple of days and I expect to again have those %#$&^*@ air bubbles spoiling the results. I have gotten better at doing this but it never fails that I will have at least two or more rather large bubbles, not certain if I am trapping air or getting solvent gas bubbles but I strongly suspect it's just my technique and that I am indeed trapping air. I will be using Accraglas this time but in the past I have used both Epoxy and Polyester resins with about the same results with both, the only time I have gotten a perfect job was with steel reinforced epoxy putty but this time I need to use something thinner and more easily worked into tight spots. Before I start I would REALLY like to hear some advice from those who are able to get good results with the Accraglas.

[Goatwhiskers]

Probably technique. I have used both Acraglas products and definitely prefer the gel, but I don't mix by whipping the stuff up in a cup. I mix either on a piece of cardboard by folding over and over. The thin type does make tiny bubbles as it reacts but have had no trouble with big ones. GW

[paul h]

You might try warming the resin and hardener by placing them in pot of hot tap water before mixing. I haven't had any issues with getting bubbles in various resins, so it sounds like you have a technique problem. Stir and fold from the edges for a few minutes, should do the trick.

[country gent]

Mixing can introduce air into the mix and cause bubbles. on some polyurethane moulds at work we put the mixed material in a vacum pot to remove air. I mix slowly and steadily in a cup and then lets set for a minute or 2 before using. this gves a little time for air to work out of the mix. I then coat both the stock and reciever and areas to be bedded with a heavy coat so when assembled there is alot of squish out to push air and gaps out. Getting a good fill and this push out helps move air pockets and fill voids better. My biggest problem is flat bottomed actions as they seem to trap more air and voids otherwise.

[lefty o]

the air bubbles definately come from mixing it too agressively. if needed mix a little longer, but do it slower and more smoothly.

[BUCKEYE BANDIT]

Wonder if the wife would loan me her FOOD SAVER as a substitute vacumn pot .

Mixing can introduce air into the mix and cause bubbles. on some polyurethane moulds at work we put the mixed material in a vacum pot to remove air. I mix slowly and steadily in a cup and then lets set for a minute or 2 before using. this gves a little time for air to work out of the mix. I then coat both the stock and reciever and areas to be bedded with a heavy coat so when assembled there is alot of squish out to push air and gaps out. Getting a good fill and this push out helps move air pockets and fill voids better. My biggest problem is flat bottomed actions as they seem to trap more air and voids otherwise.

[akajun]

try this, first ditch the acraglass, try a good non runny epoxy like Devon aluminum putty or Marine Tex, though Marine Tex has a much shorter pot life.
Next, get some good popsicle sticks or cut your own, they need to be thick, and use them to mix you epoxy on a flat surface like a paper plate, piece of cardboard, etc in a circular pattern, that minimizes the air bubbles trapped in it.
Next use those sticks to smear the epoxy on the action in a circular pattern again, then again on the inside the stock.

Last, press it in, the Epoxy should be squirting out the sides, wipe it off with acetone rags.

[andremajic]

If you want a lot of the bubbles to come to the surface after mixing use a heat gun on low. It makes it a runnier consistency when heated, and you can see the bubbles come to the surface and pop.

If you are using a thicker epoxy like marine tex, mix and fold the mixture with a flat object, like a drywall spatula. Always use excess like akajun said, so that it's oozing out the sizes when you put the action in.

If the epoxy is still "wet" and hasn't started curing you can clean it up with dry q-tips, followed with q-tips dampened in vinegar.
I haven't found an epoxy yet that doesn't clean up with vinegar. (useful if you get it on your skin too.)

Prepping the edges of the channel with painters tape makes cleanup much easier. I like to keep a garbage can directly underneath to catch any drips and it makes a convenient place to drop the q-tips.

If you still get tiny voids, you can just mix up a tiny bit of resin, smear/drip it into the holes, and replace the action until it's cured. (But that's mainly a cosmetic thing.)

Andy

[waksupi]

With Acragel, the problem arises when a person tries to get by without putting enough in to start with. You want a pretty good bead to push out when the stock and action are joined.

[scb]

Take one of these
: https://www.amazon.com/Dremel-290-01...engraving+tool

Brand doesn't matter. Tape it to the barrel and turn it on. I usually let it run a couple of hours. I keep an eye on it to be sure it doesn't get too warm.

[JWFilips]

If Acraglass Don't whip it ...fold it and give yourself enough bead so a 1/6 to 1/4 squirts out the sides

[Blackwater]

Some very good comments and advice above. One thing I learned to do with any of the various GB concoctions I've used, was to fold it in, and when I stir it, I don't get in a hurry, but go more slowly and deliberately, and mix the two parts together with a sort of 'plan' and fold it rather than "stir" it, really. This has kept bubbles down to a bare minimum, and I really wish I'd learned to warm it up beforehand, as described above. I think that would likely have also improved my results. FWIW???

[LAGS]

Besides Mixing the Air into whatever you are bedding with, Most air bubbles are formed from trapping the air between the receiver and bedding material when you set the action into the stock.
Like when doing a Barrel channel.
Put the bedding compound in the bottom of the barrel channel only, Not up the sides of the barrel channel.
Then when the barrel goes in, it pushes the bedding material Up the sides of the barrel channel and Spooges out over the forearm.
I see people try to coat the whole barrel channel and try to minimize the amount of material they use, or reduce what Spooges out.
Also a trick that keeps the Bedding compound from running out the Forend tip when the bedding is curing is to place a Rubber "O" ring on the barrel that has been coated with Johnsons Paste wax.
Place it about 1/4" ahead of the forend tip on the barrel before you set the barrel into the stock.
Then slide it back to the forend tip once the action is clamped down.
It makes a little dam so the bedding cant run out.
The bedding compound you are using should have a good hour of Working Time after it is mixed.
So , Mix it up, and let the cup sit for 15 minutes to let any air rise in the cup.
Then place the bedding compound in the Bottom of the stock, then again Let it sit and let any air bubbles come up.
Pop them , and then set the action into the stock.
Also, only clamp down the action to the stock, and Do Not Clamp the barrel down.
Let the barrel follow the path of the action being clamped, or you can be making it in to an un natural curve going down.
When your bedding is cured and then the clamps are released, the barrel springs back up causing a slight gap under the barrel at the last few inches.
And, do not take a scraper and try to pack in areas along the barrel channel or receiver that did not overflow with bedding compound.
You will be forcing air back down with the bedding compound.
There should have been enough bedding compound in the stock to make about a 1/4" Spooge Or More out the top of the stock , all along the bedded areas.
Let that Spooge Half Cure before trying to remove it.

[Walter Laich]

Take one of these
: https://www.amazon.com/Dremel-290-01...engraving+tool

Brand doesn't matter. Tape it to the barrel and turn it on. I usually let it run a couple of hours. I keep an eye on it to be sure it doesn't get too warm.

You can also use an aquarium pump from wally world for about $5

[44man]

Don't wash the bedding off. Tape the wood off and wax it anywhere that bedding will get on. Let it cure until rubbery, then cut it off with a plastic cutter. I use a chunk of hard plastic filed to a sharp edge.
Once you get all the bedding in, put what you have left in the freezer. It will not harden so the next day you can warm it up and touch up any spots.

[oldred]

Thanks for all the replies, I see several mistakes I have been making so some serious modifications to my process are definitely in order!

That bit about the vinegar for cleanup is very useful also, had no idea that vinegar would clean epoxy and I had been using Acetone on the metal or Isopropyl alcohol for skin cleanup although the alcohol didn't work all that well.

Thanks

[LAGS]

Try Denatured Alcohol not Rubbing Alcohol

[44man]

Acetone is dangerous as it penetrates skin. Yes I have done it before and working part time in a fiberglass factory everyone washed in an acetone tank. Vinegar actually works.
Wood alcohol is not safe either. The times my hands have been full of epoxy and polystyrene is crazy, don't know why I got this old. I also breathed brake pad junk in the auto industry. They made a grinder to fit drum brakes to drums. Fill the shop with dust. Those with fiberglass breathed glass all day, I used a respirator. They made big chemical tanks, go inside and grind for fittings. I bet all are now dead.

[BUCKEYE BANDIT]

Did a lot of brake work in the 60's and a lot of fiberglass in the 70's-80's and cleaned up with MEK,dumb tuff guy kid,and paying for it now.
Trying to shoot prone with COPD can be a challenge,at 65 I wear a respirator,hearing protection and saftey glasses.My Dad always said "If I had known I was gonna live this long I would have taken better care of my self".

Acetone is dangerous as it penetrates skin. Yes I have done it before and working part time in a fiberglass factory everyone washed in an acetone tank. Vinegar actually works.
Wood alcohol is not safe either. The times my hands have been full of epoxy and polystyrene is crazy, don't know why I got this old. I also breathed brake pad junk in the auto industry. They made a grinder to fit drum brakes to drums. Fill the shop with dust. Those with fiberglass breathed glass all day, I used a respirator. They made big chemical tanks, go inside and grind for fittings. I bet all are now dead.

[John 242]

I get air bubbles with Acraglas liquid; however, I rarely use the liquid. I save Acraglas liquid for filling in cavities because I can pour it into holes and get good fill-out. For normal stock bedding, I use gel and it works great.

Some of this has been mentioned already but...

I mix on a paper plate and mix the hell out of gel. I have seen more bedding jobs come out like **** because of a failure to mix the glass completely than from bubbles. More so with Marine Tex than with Acraglas, but it happens. Brownells says to mix for four minutes, so MIX FOR FOUR MINUTES! Don't shortcut. I've seen soft spots in bedding jobs that don't harden correctly because of poor mixing.

If you're using Acraglas gel and the white one (resin?) becomes stiff or kinda crispy (for lack of a better description) you can nuke it in the microwave for a few. This will make it supple again. At school we use big tubs of Acraglas and the students are terrible about leaving the lids off. 30 seconds in the microwave makes everything right again. Small containers would require less time.

A very good way to avoid bubbles when using a gel type epoxy is to "butter" both the metal and the stock. You want to spread compound on the metal and the wood, both and kinda heavy. This usually results in a void free bedding job for me and it seems to work for just about everyone else that tries it. Some peoples kids though...

I try to always mix more glass than I think I need. I want the stuff to squeeze out all over the place. I mask up the stock with painter's tape and use release agent (Johnson's paste wax or Acra-release in the spray can) anywhere I might get glass on the metal. If you use paste wax, don't get carried away. You only need a thin coat. Don't glob it on or you'll ruin your bedding job. For hard to reach areas you can spread paste wax with a small acid brush. Otherwise, I use my fingers to spread a light coat. The wax should dry on metal and become... waxed. Not gooey.

If you get a little Acraglas gel somewhere you don't want it, including your hands, you can wipe it away while it's still wet with a little white vinegar and a paper towel.

If you use the dye that comes with Acraglas, use it sparingly. A small drop goes a long way.