Seeking advice: silicone or epoxy?

[Sheb]

I recently caught the DE shavingbug and have found a new passion! What with all the cool soaps, creams, pre andpost shaves, after shaves, razors, blades, etc. the investment adds up quickly.So I decided to make a couple of brushes. The first handle is complete. Itis white oak with black paint rubbed into the grain, walnut stain, and Tru OilFinish. It is 45mm tall and about 42mm square. The knot is TGN Finest 3-bandbadger, 24mm to be set into a 26mm hole at 50mm loft.



I had thought to set it with a two partwaterproof epoxy until I read this post by “rudyt” in another thread: “I would suggest staying away from epoxy anduse good old GE Silicone. It's more than strong enough, is completelywaterproof, and best of all, you can remove the knot at a later time with asolid sharp twist -- really useful if you're playing with getting the perfectloft.”So now I’m conflicted. (Lord! Don’tlet my wife know I said that!) Silicone seems to offer some advantages that I findinteresting. What are the disadvantages --if any? If anyone has experience with epoxy versus silicone I’d love to hearyour advice.

 

[cpacamper]

Gorgeous brush!

I am also interested in hearing thoughts on the topic.

 

[Big Jim]

It is hard to argue with Rudy, but I would use epoxy unless you know you may want to play around with loft settings. Even then, I would end up with epoxy once all was said and done.

But that's just me. YMMV

And I almost forgot. That is a gorgeous brush, both handle and knot. Nice job.

 

[Marquis_De_Wyld]

I have used both materials for other projects, I have to say - they both have aspects that are useful.
For rigid to rigid bonding, epoxy just owns compared to silicone and yes, it is waterproof once cured... However, the rigidity can prove an issue if one material is flexible. The movement can cause cracking, which of course would allow water to permeate into an area that would be better kept dry.
Silicone, in the context of trying to keep a flexible material adhered to a rigid one would be the one I would opt for in that context.
although it can be more costly than epoxy resins and glues.

 

[Sheb]

Thanks for the input guys! Marquis, I understand what you are saying and appreciate your "rigid to flexible bonding" insight. I think of wood as "flexible" and I guess the plastic (?) base of the knot should also be considered flexible? So it sounds like silicone is a good way to go. Do you have a recommendation for a particular brand or product? Am I looking for an adhesive with silicone in it, or just silicone? Feel kinda silly asking but I'm totally unfamiliar with this material. My experience is with wood glues and a little with CA adhesive. Thanks again for your advice, it is greatly appreciated.

 

[labrax]

I have used both - and have a big silvertip in a whipped dog handle that I used silicone sealant on. It has probably had a dozen uses on it and it is fine. I shake the brush out after use and wipe it on a microfleece towel to dry a lot of the water off of it - and no problem with the shaking of the brush and the knot staying put.

 

[blzrfn]

I always use silicone adhesive when assembling a new restoration project. Only when I am certain that I will enjoy the loft setting and handle/knot pairing will I use epoxy. Silicone is easier, bonds well but is not permanent, and allows for changes to be made in the event you aren't 100% satisfied. Sometimes raising or lowering the loft as well as increasing the bore size of the knot hole can drastically change the characteristics of a brush. I can't think of a good reason to go straight to epoxy unless you are 100% sure of the choices you have made.

 

[Rudy Vey]

It is hard to argue with Rudy, but I would use epoxy unless you know you may want to play around with loft settings. Even then, I would end up with epoxy once all was said and done.

But that's just me. YMMV

And I almost forgot. That is a gorgeous brush, both handle and knot. Nice job.

I think this was a different Rudy than I - my recommendation is always 2-part epoxy!!

 

[rudyt]

Yeah, I'm "The Other Rudy". Here's what I have always used, good old GE Silicone:

http://www.homedepot.ca/product/ge-silicone-i-all-purpose-sealants-clear-85-ml/941928

Another advantage to the silicone over the epoxy is that you can try the silicone, and if you don't like it for whatever reason, you can always pop out the knot, clean out the hole, then switch to epoxy. It's almost impossible to go the other way.

I have brushes that have been glued in with silicone *years* ago and not one has ever loosened or fallen out.

 

[Sheb]

great discussion guys! cant thank you enough for sharing your expertise and experience with a newbie! thanks too for the link to the Home Depot page rudyt. I've decided to try the silicone, so I will pick up a tube of GE tomorrow. I have already sealed the sides and bottom of the knot hole with epoxy - - did that back when I thought epoxy was the only viable solution. I wanted to be sure the entire inside of the hole was sealed all the way to the top edge, not just in the bottom where the knot will "seat". I don't imagine the silicone will have a problem adhering too the epoxy coating - - do you?

 

[BSAGuy]

If Rudy Vey uses epoxy, that's all I need to know.

 

[Marquis_De_Wyld]

Thanks for the input guys! Marquis, I understand what you are saying and appreciate your "rigid to flexible bonding" insight. I think of wood as "flexible" and I guess the plastic (?) base of the knot should also be considered flexible? So it sounds like silicone is a good way to go. Do you have a recommendation for a particular brand or product? Am I looking for an adhesive with silicone in it, or just silicone? Feel kinda silly asking but I'm totally unfamiliar with this material. My experience is with wood glues and a little with CA adhesive. Thanks again for your advice, it is greatly appreciated.

Right, let's break it down. As per the description of what you're bonding... In this instance, the wood is to regarded the hard material. The plastic as the flexible. There is also a consideration that as the hairs of the brush move around, the substrate (aka plastic) they are bonded to would also move, although these movement would be pretty insubstantial... There would still be movement.
As for suppliers, most good hardware store would be able to provide a fairly broad array of silicone adhesives.
should you wish to look on line, I have found a detailed guide from a company called master bond...

http://www.masterbond.com/techtips/why-use-silicone-adhesive

They produce both types, so I see no reason why they would have any bias in recommending one over the other, aside from the specific needs of the job to be done.

 

[rudyt]

I don't imagine the silicone will have a problem adhering too the epoxy coating - - do you?

There's a very comprehensive list of materials the silicone will stick to on the package, but my experience is it sticks to pretty much everything. I had a leaky skylight on my roof, and put a bead of silicone between the skylight and the vinyl flashing and it's been almost 10 years with no leaks in wild temperature extremes. Silicone is tenacious.

 

[armybuck041]

I ended up using Gorilla Glue for my Pro49 to Rubberset 400 project as at that moment, it was the only adhesive I had in the house. Worked perfectly.

 

[nemo]

I use silicone RTV without any problems long term. Nothing needs to be more permanent for my usage, the hairs will all out of the knot before the silicone fails.

I've used it for years in automotive and household applications, so easy and no fuss to use.

 

[SPR809]

I ended up using Gorilla Glue for my Pro49 to Rubberset 400 project as at that moment, it was the only adhesive I had in the house. Worked perfectly.

I did the same thing for the same reason - worked great, but I doubt I'll ever remove the knot without destroying it.

 

[Skeezixx]

I always use silicone for the above mentioned reasons and because it has a service temperature of over 400 degrees F. The only time I used epoxy it failed while soaking the brush in hot water. Most two part epoxies have a service temperature of around 120F.

Also, if you accidentally get a small amount of silicone in the hair above the handle it's easily removed with a comb. Try that with epoxy.

 

[Rudy Vey]

I always use silicone for the above mentioned reasons and because it has a service temperature of over 400 degrees F. The only time I used epoxy it failed while soaking the brush in hot water. Most two part epoxies have a service temperature of around 120F.

Also, if you accidentally get a small amount of silicone in the hair above the handle it's easily removed with a comb. Try that with epoxy.

Most brush companies do not recommend to use hotter water than 100-110 max. anyway (HL Thaeter says "max. 40C", which is 104F).
Do not forget that I am a brush maker and sell brushes. My customers expect the knot to stay in the handle and often specify the loft the knot should be set in, therefore, my use of epoxy glue.

 

[Marquis_De_Wyld]

Yeah, I'm "The Other Rudy". Here's what I have always used, good old GE Silicone:

http://www.homedepot.ca/product/ge-silicone-i-all-purpose-sealants-clear-85-ml/941928

Another advantage to the silicone over the epoxy is that you can try the silicone, and if you don't like it for whatever reason, you can always pop out the knot, clean out the hole, then switch to epoxy. It's almost impossible to go the other way.

I have brushes that have been glued in with silicone *years* ago and not one has ever loosened or fallen out.

Noticed that it is not recommended for oily woods and stone, which to me makes sense (in context; RTV silicone mold releases tend to be oil/wax based). Does that mean that for some materials an alternative should need to be considered?

For the sake of discussion, would epoxy be suited more for something like soapstone?

Also, if you wish to treat the wood with oils I am going to assume (as I have no experience whatsoever of making brushes) you have to do it post assembly?

 

[rudyt]

For plastic and resin handles there's no issue. For all my wooden handles, I almost always seal them completely before gluing in the knot. Sometimes I get lazy and don't seal inside the hole if the wood is oak, maple or cherry. I have yet to have a knot fall out.

If you want to oil treat, I would only do it outside and avoid the hole. If you do this, pre or post doesn't matter.

Sorry, but I'm by no means a glue expert, so I have no clue what works best for soapstone.