Is smooth-on this forgiving?

[Don Armstrong]

PLEASE don't take this the wrong way but there seems to be multiple ways to use smooth-on. I am unsure which way to go. Some mix 1-1 up to  2-1. Some cook at 150 for 2 hours and some cook at 180 for 6 hours and others anywhere in between. Also, some use 60 lbs. of air pressure on there forms and some up to 75 lbs, so air pressure doesn't seem to be a factor.It seems that you can't go wrong with smooth-on. Does it really work anyway you use it? Thanks, Don

[Bert Frelink]

Don,
There is a a reason 90% of Bowyers use smooth-on.
Bert.

[Canadabowyer]

Don, smooth-on is a very versitile and forgiving glue, but you must use it properly.On the can it says "for maximum bond strength mix equal parts A and B by VOLUME" and "for maximum heat resistance mix 2A TO 1B by WEIGHT". "Cures in 16 houres at 25 C, more rapidly at temperatures up to 100 C." I choose to go for bond strength so I mix it 1 to 1 by volume. This mixture is "non critical" within reason. In my experience simple measuring cups are close enough. I cure bows with heat strips timing 1 hour after they reach 150-180 F and so far have had no problems. When I first started I used the bow oven and cured 6 hours with the thermostat provided from Binghams which is supposed to keep the oven between 150 F and 180F, again with no problems. When I do riser glue ups I cure without heat but find it takes at least 48 hours at cool room temp(65F) for the glue to cure to the point where it is cured enough to sand or grind without gumming up your sanding belts. Also by curing your risers at room temps it will only strengthen the bond when you cure the whole bow at higher temps. Thats my eperience with smooth on and I wouldn't even try another glue because it has worked so good for me. If you have specific questions feel free to PM me, I'll help if I can.  Bob

[Don Armstrong]

I may have not made my point. I am going to use smooth-on and think it's the best for glass bow. There seems to be so many varibles to using it. I am going for the middle of the road   . I will mix 1 to 1 and use about 70 lbs of pressure but still am not sure what is best. There are many people on this site that make some absolutly beautiful bows but seem to use much different mixtures of smooth-on and large variations of pressue on their forms. Thanks for all the help, Don

[matts2]

Don, You will have a hard time getting "the best way" answer because like you said, everyone does it different and they all have great success.  Just follow the directions and mix 1:1 and put 60-70lbs of pressure in the hose.  Curing in oven at 150-180 degrees for 4-6 hours.  Air dry in normal room temp for at least 24 hours or use heat strips which will take anywhere between 30 minutes to 1.5 hours.  It all works.  Do what works best for you.

[monterey]

Don, I have used Epon Versamid in the past, but had not layed up a bow in several years.  This week I layed one up using Smooth-On and I'll never use Epon again!  The smooth on literally smooths on beautifully and is a (relative) pleasure to work with.

I used 1 : 1 and cured at 160 deg for eight hours.  Reading the previous posts in this thread, it apparently is over-kill on the time.  I always used eight hours with Epon and automatically did the same with Smooth-on.  I'll be laying up another in the next week or so and this time will go with four hours.

I use the Bingham thermostat and have found that it holds my oven at an even 160.

[don s]

i believe getting the air pressure correct is to eleminate the possibility of too much glue being squeezed out and causing your limbs to be glue starved. just how do you glass guys know what psi is correct? trial and error? don

[jsweka]

just how do you glass guys know what psi is correct?

Honestly, I don't know what is correct.  I just set the air compressor to 60 lbs and inflate.  When I first started building bows, I read somewhere to use 60 lbs, so I did, and all my bows have held together so far.

[StoneAK]

Matts2 is right I have used smooth on many different ways because I haven't built a bow oven yet. I have let it set for 24 hours in my shop and worked just fine. I am using it now let it set in the sun for 5 hours then moved it in to the room with the wood stove and let it sit in there for the rest of the night and seems to be setting up real nice

[Lost Creek Bows]

I go 5 hours at 170 deg. and 80 to 90 psi. Its a great product and all I use.

[**DONOTDELETE**]

one to one by volume is pretty close to the same as 100:83 by weight. But i always seem to have a bit of hardener left in the can when the resin is gone, so it's not exactly the same.... but... it sure is a lot easier to get your mixture the same every time using a scale, rather than volume.

60-70 pounds works just fine. any more than that can "potentially" do damage to the limbs if your spacing for the air hose isn't just right.

[fujimo]

so tell me how you glue on the tips,
1.do you put the limbs back in the oven-
2.use a different glue, or
3.cold cure the smooth on

[jsweka]

I use Kwik-It (a type of superglue) for the tips.

[Lee Robinson .]

High air hose pressure (80-100 psi) isn't going to damage the materials used unless you have a bump in your form that concentrates that pressure to a pressure point. The key is EVEN distribution. Like scuba diving...we can take pressure as long as it is EVENLY distributed. 20 pounds can damage materials if it is placed on a concentrated point like a nail.

[**DONOTDELETE**]

here what i use on my tips... works excellent.

 

[Dick in Seattle]

re Smooth On flexibility, I haven't done it since I build an oven, but I've talked to a number of folks who simply do their layups in the summer, wait for a sunny day, do the layup in the morning and put the whole thing in a closed up car for the afternoon.

[monterey]

Regarding tips, I use the same as what I use to lay up the bow.  Versamid in the past, but now smooth on.  I clamp the overlays onto the tips and place a light bulb underneath each tip.  An automotive drop light works as does just about any portable bulb holder with a reflective ability.

Don't use those high heat lamps with the tubes (can't remember what they are called).  They can get too hot.  Melted a synthetic gun stock with one once while glass bedding!!!  :eek: