O.K. Gang: I came back to modeling after about 5 years and no K & B resin
any more. So what are you guys using now. I have the Concepts 1/4 Fleet
Biplane. The cowel is made up from balsa blocks. I used to just coat with
the resin sand and paint. What a good alternative ??
Denis Winters <
And who makes the "Epoxy Resin" Not sure I have seen this ??
or maybee I wasn't lookin ??
There is a resin available,usually in larger quanities. I usually just thin
epoxy glue (SIG brand ) with acetone,it will also slow down the drying time.
There aren't any items that replace the old K&B Polyester Finishing Resin. At
least I haven't found one.
OTOH, there is a good item that works well -- not like K&B -- and doesn't smell
nearly as bad as K&B.
That is ZAP epoxy FINISHING resin. It is more brittle and doesn't have the
sanding qualities but a couple coats will seal things up, especially over
glass. Primer is still required. Sanding can be enhanced with addition of some
micro-balloons, however some thinner may be required. Alcohol or epoxy thinner
from the hardware/home stores will work.
Contrary to what another poster said, epoxy resin is far LESS brittle than
polyester (K&B, etc.) resin. That is why most people switched to epoxy many
years ago. Not only that, most of the better fiberglass fuselages, cowls,
etc. use epoxy resin for the same reason. Epoxy remains somewhat flexible
while polyester resin gets more and more brittle with age.
If you still want polyester resin, any boat store like Boat U.S.,
Westmarine, etc. will have it. They will also have epoxy resin.
Last time I looked (it's been a while) Sig sold a polyester finishing resin
that was equal to, if not the same as, the old K&B stuff. Try their web
You can also go to most marine hardware stores and buy "finishing" or
"surfacing" resin, which is also the same polyester stuff. Beware that their
are several flavors of resin in a marine store. There is a "bonding" resin
which is designed to adhere the cloth to the surface being glassed. It does
not ever get beyond the tacky stage of cure. Then there is a "covering"
resin designed to go over the bonding stuff and make a hard cure. Then there
is the "finishing" stuff designed to be easy(ier) to sand. TAP plasics also
sell a polyester resin, although I don't believe it is of the "finishing"
flavor. The finishing resin has more wax in it to aid in the sanding
The information above could use a bit of amplification:
For polyester resin (the stuff you'll find at the auto-body shop,
for maybe$20/gallon, or at Boat/US, etc., and whose 'hardening
agent' might be 1 oz to the gallon of resin): * The resin is constantly "hardening", so a 10-year-old bucket of
resin is likely to be just a plastic rock. The "hardener" is really
a *catalyst* (typically Methyl-Ethyl-Ketone (MEK) Peroxide), which
encourages the reaction to go faster. You adjust the amount of catalyst
depending on the temperature at which you're working, since warmth
is ALSO a catalyst for the reaction.
* Bonding resin is "air inhibited": it reaches a soft cure, but remains
tacky as long as it's in contact with air. (So when you put on a new
layer of fiberglass, the lower layer turns hard, rather than remaining
a gelatinous goo -- wouldn't be very strong, would it?). * Finishing resin has some kind of 'wax' in it, which floats to the
surface and keeps air from getting to the resin during cure, which
allows it to harden up properly.
* The wax, as far as I know, is of no use in sanding. Indeed, it
tends to get mixed up with the sanding process and leave your
surface waxy, which is hard to paint; you need to use a special
de-waxing agent to get the surface ready to paint well.
Methinks this person NEVER used K&B Finishing resin. It ain't jest all the
I used several resins finishing CL speed models, and RC models.
IMO there never WAS or has there BEEN anything to compare to the old K&B
FINISHING resin or the K&B Super Poxy paints (Not the later line) especially
when factoring in "User Friendly".
I have not yet used the newer Klass Kote line but I will as soon as I need a
good finish better than polyurethane.
BTW Sig is good, but the old K&B it ain't.
* The hardening process often generates something called an "amide
blush" (a Google search on that term will give you more info than
you could ever want), which should be removed with a mild detergent
solution or it'll screw up paint adhesion for all but the most
aggressive paints. Some epoxy manufacturers claim to have no-blush
epoxies; some epoxy users dispute those claims. (Surprise!)
I recomended Sig 30 minute epoxy because it doesn't have this problem and is
easy to sand and doesn't clog up the sandpaper.
When i was building RC racing Hydro's that were made of plywood and foam,i
would use a mixture of the Sig epoxy glue and acetone to thin it like water so
it wood soak into the wood. It sanded very easy,i then sprayed a primer coat on
and it was readt to paint. DOUG
Welllll, I have been painting airplanes since about 1955. I used a LOT of
K&B resin and paint. My only complaint was always that it was too brittle. I
switched my finishes to "Imron" and other polyurethane based two part auto
paints because it didn't 'chip' so bad as K&B. I switched all of my resin
use to epoxy for the same reason. I built formula 1 pylon racers by the
boatload for people back in the 70's and 70's. Since I had a lot of K&B on
hand, I offered the airplanes finished either with K&B or Imron. NOBODY
opted for the K&B. The secrets are in the preparation and application. You
DO HAVE TO KNOW what you're doing to get as good a finish with the
polyurethane. The K&B paints were so thin you could pretty much shoot em
right out of the can. The poly's require reducing and you'd better get it
right. More amatuer painters probably found K&B easier. I didn't. I have
now switched to giant scale warbirds and use acrylic (latex house paint)
exclusively. If you're not looking for super shiny, it's the best yet. You
DO have to use High Volume Low Pressure spray equipment to get a really good
finish with it so it's probably not the best for less experienced painters.
The main thing is, use what works best for you. I haven't looked at the
Klass Kote either because I am really enjoying the HUGE cost advantage of
On 10/2/2004 4:53 PM Ted shuffled out of his cave and grunted these
great (and sometimes not so great) words of knowledge:
Why not look into 1/2 oz glass cloth applied with water base
polyurethane ? Strong, lightweight finish that is easy to sand and
takes a finish quite well AND THERE ARE NO FUMES.
There are many paints that are better than just about anything
model-specific. Modern automotive finishes are far more flexible than the
average hobby product. you can add the flex additives to many of them and
they will not break on the new plastic bumpers.
I have used auto base coat/clear coat systems on several planes. Not only
is it lighter, but also nearly indestructible and fuel PROOF to at least 60%
nitro (the highest I ever used).
Regarding resins, I have always used Z-Poxy finishing resin. It is
flexible, easy to sand and holds primers very well. May epoxy resins have a
hard time accepting primers unless the surface is thoroughly sanded first.
SIG polyester resin is as close as you will find and works well and
should be available at you LHS.
A good altenative is Tap Plastics Super-Hard Epoxy Resin. Used to go
by the name "4 to 1 Epoxy." It has a very hard cure and sands very
Great for doing what you have in mind. Also for 'lost mold' cowls
> O.K. Gang: I came back to modeling after about 5 years and no K & B resin
> any more. So what are you guys using now. I have the Concepts 1/4 Fleet
> Biplane. The cowel is made up from balsa blocks. I used to just coat with
> the resin sand and paint. What a good alternative ??
> Denis Winters
Where do you get this water base polyurethane, I am also coming back to
modeling after about 3 years. I started the P-39 Airacobra back then, I plan
to finish and fiberglass and paint the plane. This thread has been great for
me, I have been trying my first glassing recently. You guys keep going with
as many details as possible. Also I did not know you could thin Epoxy with
Acetone, is this okay to do. I recently glassed the center section of the
wing on a Bingo kit for practice, also the stab and fin. It turned out okay
but I would like to improve before starting on the P-39. I used the very
expensive z-poxy and would like to find a cheaper alternative. I also found
it interesting that one of the guys is using ordinary house paint, I would
love some details on that if you read my post.
Thanks (great thread)