Looking for a balsa filler that also add some hardness

[BRS Hobbies]

Anyone know of a balsa filler that also adds some hardness? I figured it would come in handy for balsa nose cones and fins.

 

[SolarYellow]

Soak with thin CA.

 

[neil_w]

I always use thin CA on my balsa noses, in some combination with wood filler and filler/primer. I haven't been able to figure out how to get a completely uniform smooth surface just with CA. But it does create a nice hard shell around the nose.

Papering is my preferred method on fins.

 

[kuririn]

Minwax wood hardener.
Paint until the wood is saturated (glossy coating).
Fills the pores with an acrylic.
Not as hard as thin CA but easier to apply, easier to clean up, cheaper, and easier to sand.
I also use it for mushy cardboard tubes.
I do use thin CA for the tips of pointy nose cones and failure lines on balsa fins.
And to repair creases on cardboard tubes.

 

[SolarYellow]

I always use thin CA on my balsa noses, in some combination with wood filler and filler/primer.

@hcmbanjo appears to be consistent in his thinned CWF first, then sand down and finally soak with thin CA:
https://modelrocketbuilding.blogspot.com/2013/09/semroc-cherokee-d-build-part-5-nose.htmlhttps://modelrocketbuilding.blogspot.com/2018/05/estes-mini-heli-007272-build-part-15.html
Many others if you search the site.

I might do thin CA first so it can soak into the grain more and harden it to a greater depth, then sand that and off to whatever makes sense to me that day as far as primer, filler, and filler-primer.

 

[hcmbanjo]

@hcmbanjo appears to be consistent in his thinned CWF first, then sand down and finally soak with thin CA:
https://modelrocketbuilding.blogspot.com/2013/09/semroc-cherokee-d-build-part-5-nose.htmlhttps://modelrocketbuilding.blogspot.com/2018/05/estes-mini-heli-007272-build-part-15.html
Many others if you search the site.

I might do thin CA first so it can soak into the grain more and harden it to a greater depth, then sand that and off to whatever makes sense to me that day as far as primer, filler, and filler-primer.

I don't normally use CA on nose cones.

 

[Back_at_it]

Warmed epoxy works great for this. Mix up a batch then set the mixed cup in hot water for a few minutes. Next break out the hair dryer / heat gun and warm up the parts.

Brush on a coat of epoxy then use the heat gun again to level it. Wait about 5 mins for it to soak in then do a second coat. Be sure to use heat at the end of each step to level the epoxy.

The fins will be very stiff afterward and little to no sanding will be required to make them smooth. You might need to knock off a couple of bumps here and there but that is easy with some 400 grit. An added benefit is that the fins are now waterproof.

 

[Blast it Tom!]

Warmed epoxy works great for this. Mix up a batch then set the mixed cup in hot water for a few minutes. Next break out the hair dryer / heat gun and want up the parts.

Brush on a coat of epoxy then use the heat gun again to level it. Wait about 5 mins for it to soak in then do a second coat. Be sure to use heat at the end of each step to level the epoxy.

The fins will be very stiff afterward and little to no sanding will be required to make them smooth. You might need to knock off a couple of bumps here and there but that is easy with some 400 grit. An added benefit is that the fins are now waterproof.

Sounds good but I'm curious as to what type of epoxy you use. And of course, at the same time the heat is softening it, it's kicking it as well. Any time constraints that way?

 

[cls]

Shellac works well for me. Used it on fins and nose cones of recent LPR models. Kinda forgot about it but a friend suggested it. I used a couple coats, it comes out hard, but sandable, smooth.

 

[Back_at_it]

Sounds good but I'm curious as to what type of epoxy you use. And of course, at the same time the heat is softening it, it's kicking it as well. Any time constraints that way?

This method works great with BSI 30 min. and T-88 epoxies. The BSI requires you to work pretty quickly as the heating does reduce it's pot life down to about 12-15 mins. The T-88 is still a liquid even at the 30 min. mark. I wouldn't try this with any of the 5 min / 15 min stuff.

I was a die hard BSI fan for years and I still use BSI for certain things (it's a fine product) but for 95% of my epoxy I'm using T-88. I like the extended working time and I find that the finish is harder once fully cured. It's easier to sand and doesn't gum up the sand paper. The one downside of T-88 is the cure time. It is thick at the 4 hrs. mark but really needs 8 hrs. before you can handle it. Full cure is about 24 hrs. depending on thick you put it on but once dry it's like a rock.

Also like that I can get larger quantities of T-88. If I need a 5 min epoxy then BSI is still my choice.

 

[Daddyisabar]

How about good ole Dope? Gone the way of the Dodo...

 

[Blast it Tom!]

How about good ole Dope?

I replied further up the thread....

Oh, wait, you mean that butyrate base hot fuel proof stuff with the fumes? Got two jars in the drawer, when I learned about CWF as a n00b BAR, we'll, they're still sitting there in the drawer!

 

[Daddyisabar]

I replied further up the thread....

Oh, wait, you mean that butyrate base hot fuel proof stuff with the fumes? Got two jars in the drawer, when I learned about CWF as a n00b BAR, we'll, they're still sitting there in the drawer!

Time to get "Sniffing" old school style. A little dopey but really works well. Fast dry, strengthens, easy to sand and great results. Learn the ways of proper thinning and old world craftsmanship. Take a giant leap back to the 20th Century.