Silicone adhesive to set knots

[grump]

A few questions those that use silicone adhesive to set your knots.

What do you use?

If you want to change the loft how do you remove it?

How long does it last?

Also wanted to add, before someone asks why, that this is to try different knots in a handle, from different places, at different lofts, before making them permanent.

I normally use epoxy to permanently set the knot.

 

[mattdenicola]

A few questions those that use silicone adhesive to set your knots.

What do you use?

I use Permatex RTV silicone adhesive ... any clear setting silicone glue will be fine.

If you want to change the loft how do you remove it?

Just pull. Don't get too crazy and damage the knot. Depending how well the seal formed and how much glue you used, the pull force required will obviously be different. Some people do a "test" setup with just a tiny bit of the glue. This is extremely easy to remove ... just give it a quick pull. If you are setting it more permanently and used enough glue to get a seal, it will take a bit more time ... 15-20 seconds of good consistent negative pressure and the knot should come out. You shouldn't really need to twist it around much if at all.

How long does it last?

I've only been using this for 6 months or so. So at least 6 months. But there are others on here who have been doing this for longer. I've never heard of a knt failure using the silicone glue. I see no reason why it would ever give out.

 

[blzrfn]

Ditto to everything Matt said. When I first set a knot I only use a pea sized dollop so that I can easily remove the knot and adjust if necessary. Using this small amount I have had knots fall out after a few shaves, but at that point I know if I want to adjust the loft or make it permanent anyways. When I am ready to finalize my brush I apply the adhesive about a 1/16" around the entire base of the bore and let it sit for a minute before inserting the knot. As I insert the knot I press it in firmly and rotate the knot back and forth 90 degrees a couple times to ensure there are no air bubbles. Using this method I have not had any knots come loose but even if I did it is a very simple process to repeat.

 

[grump]

Thanks guys!

 

[shavervinnie]

RTV used here as well. Seems to work fine for my needs.

 

[Snargle]

I've got a couple of brushes that had the knots cemented in with RTV Silicone adhesive. There's been no problems with two plus years of regular usage.

 

[jmak642]

You should be able to use just about any silicone as a relatively good adhesive, but things with lower shore hardness are going to be easier to rip loose if you want them loose. Look for something that will set up at a shore hardness of less than say 50A or any of the shore 0 or 00 options available. It should be relatively easy to remove a small dab of any of those. Silicone will stick to anything that doesn't have release agent (cooking spray works) on it for the most part, as long as its relatively clean and free of excessive dust. A good way to read this is: the clear silicone caulk from home depot will work just fine, but if you are really worried about it, the are specialized options out there.

If I was choosing a silicone to use as an adhesive in a shaving brush, I'd be around shore 40A, something like http://www.smooth-on.com/Silicone-Rubber-an/c2_1115_1131/index.html. That should hold it in there no matter what you do if you put enough to cover the base of the knot, even if you boil it, it isn't going anywhere. If you use less, and you pull on the knot pretty hard, it would come out. If i wanted to be able to remove it easily, I'd go to something much softer with a much lower tear strength, like http://www.smooth-on.com/Platinum-Cure-Sili/c1115_1130/index.html. That would hold it in there for general use, be somewhat resistant to heat and water, but still if you intended for it to happen, you could pull the knot right out of there even if you covered the base of the knot completely with the silicone.

All that said, unless you are doing a whole lot of this, just get the clear silicone caulk from home depot and be happy. However you decide to go, keep in mind that less is more, and silicone sticks to everything.