Caulking Gun AAS Filtering


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Aug 26, 2012
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posted by: bass

Using a regular caulking gun for your steroid filtering
Okay, here is how you do it. Buy a regular ordinary caulking gun. Notice on the underside, near the business end, there is a little wire doodad. This folds out and is designed to be used to pierce the seal in a new tube of caulking. Normally it is folded out of the way. We can use that later, so make sure your caulking gun has one.

Set up your vial as usual, with a 18 to 21ga pin for filling, a whatman attached to the pin, and a second pin, of any size you got, for a vent. In addition to that stuff, you also need to loop a rubber band around the vial neck. Run one bight (one doubled-up end) through the other and cinch it tight. You will use this to suspend the vial so it does not fall off.

The procedure is to first draw up some unfiltered gear in a big syringe. A 10cc works okay but you may as well go with a 20cc or even bigger. Do not completely fill the syringe. Leave about 1/4 of it empty, i.e. with air. You will need this air bubble.

Remove the pin that you used to draw up the unfiltered gear and set it aside until you draw the next load. Attach the syringe to the whatman on the sterile vial. Place the syringe and whatman in the body of the caulking gun. Loop the long end of the rubber band over the wire doodad. Press the caulking gun plunger down against the plunger of the syringe.

In use, the caulking gun will be pointing down at the floor, with the whatman and syringe inside the body of the gun, and the vial suspended underneath the end of the gun. With a small vial, you could just trust the vial stopper to grip the pin enough to hold it on. With a larger vial, that won't do at all. The rubber band is a bit of insurance, to keep the vial from simply slipping off the pin and falling, in which case you are filtering gear only to have it dribble on your carpet.

The air bubble will serve as a pressure reservoir. Squeezing the handle of the caulking gun will ratchet the plunger in and press the syringe plunger in, as well. The air bubble will compress. Look for the bubble to be reduced to about 1/4 of its unpressurized size. You should see gear begin to flow through the filter and out of the tip of the needle and into the sterile vial. It might be fast, if you have a new filter and warm or very thin oil. It will be slower with thicker gear and slower still if the filter is getting clogged. No biggie. If it is running fast, you can just hold it in your hand and keep squeezing it through. If it is slower, just pressurize the syringe, hang the caulking gun by its handle over the front of a bureau drawer, and walk away. Come back later and repressurize as necessary. When you come back and all of the gear has been pressed through the filter, release the caulking gun plunger, remove the syringe, replace the drawing needle and draw up another load. Repeat as necessary.

You can have several guns going at once, if you like. Just reload or repressurize each, in turn, as needed. With 5 guns, for instance, you can process a large batch in 1/5 the time that it would take with a single gun. Maybe 1/100 the time it would take to filter totally by hand pressure, and your fingers will thank you.

As long as gear will pass, however slowly, through the filter, no need to change it. Hand filtering calls for frequent changes, since it is difficult to keep up the pressure for very long. So, you quickly save on filters what you spent on caulking guns. It does not matter how long it takes, either, since you need only to check on it at your convenience.

Last-minute tips:

Be careful with the whatman. Too much pressure could deform it and cause a failure.

You can use a blowdryer to keep things warm and keep the oil running freely.



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Sep 4, 2016
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Don't waste the calk either j.... the shadow..... way cheaper than mediphorm :D


SI Founding Member
Aug 7, 2012
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I used this method for a long time! I use a Harbor Freight vacuum pump kit, now.