wally3185

My Feedback: (26)

Why? I thought everyone on the internet (especially forums like this) are experts




The only experts I know, are my wife and her mother. But the only thing they know about, is everything.

Charlie P.

I've owned 10 fiberglass sailboats (one a 1964)and two wood ones; one of which was a 15 ft "tack-n-tape" plan I built from scratch and my first wasa Sunfish that blew off a roof rack on the highway and was for sale "as is" and cheap . . . and missingabout the front6" of the bow. I know a LOT about epoxy. Mostly through Aw**** University home study courses. ;-)

I used to buy West System (and before that System Three)by the gallon, but now only by the quart.

http://www.westsystem.com/ss/assets/...12%20Part1.pdf

http://www.systemthree.com/reslibrar...Epoxy_Book.pdf

Rodney

If you use rubbing alcohol for thinning, you will eventually get a batch of sticky uncured epoxy mess. It is wise to take West Bends recommendations and not use alcohol for thinning unless you can accept a not perfect water seal and an occasional mess.

j.duncker

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Sorry that is not the case, old fashioned cellulose dope is not fuel proof.

eddieC

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Modern dope is butyrate, I don't know if cellulose dope is even available. [:-] 

Butyrate is fuelproof to 15%, beyond that very fuel resistant to 30%, and I'm talking immersion for days to compromise the dope.

JohnBuckner

My Feedback: (1)

Sorry Rodney that is like saying never walk on the sidewalk, you might get hit by a car!

Your description of a mess has never happened to me and if you carefully drip to a milky white as I described earlier then it won,t and its never failed to harden to a fine and effective fuel proofing layer for me or any I have taught the technique to.

John

wpbrown

My Feedback: (1)

This information is in the June 2012 Fly RC Magazine on page 101. It is from Bob Smith Industries about how to thin or color epoxy...

"Heating epoxy will make it thinner, but this also lowers your working time. BSI’s Finish-Cure is thin enough naturally to be brushed on. 91%-99% isopropyl alcohol is the best solvent to add to epoxy for thinning and it is available at most drug stores. Usually adding no more than 10% is enough to sufficiently lower the viscosity of the epoxy. Do not use rubbing alcohol. While it can be used for the cleanup of uncured epoxy, it contains 30% water and has an adverse affect on the curing process. Acetone can be used but is more likely to change the cured properties of the epoxy. Acrylic paint can be used to color epoxy, but some paint stores have tubes of concentrated tints in paste form for acrylic/latex paints that come in many colors. These work best for coloring epoxy."

This is also on their website.

rotoman

jaka

Hi!
Old fashioned dope does not work! It cannot stand methanol and nitro!
Ca glue, 24hour epoxy or 2-part acrylic car paint is much better!

landeck

My Feedback: (1)

Jaka, old fashioned nitrate and modern nitrate dope will not work but old fashioned buytrate and new fashioned buytrate dope does work because it is fuel proof.

Bruce

eddieC

My Feedback: (2)

I don't know anyone who uses 'old fashioned dope'!  I don't know where to even buy old fashioned dope!

Old-fashioned cellulose dope went out of use for us decades ago!

JohnBuckner

My Feedback: (1)

Oh my, I will never know how we survived all those years using dope to fuel proof our engine compartments but heck survive we did[]


But wait a minute, oh ya I know we used butyrate over the nitrate, yes-sir-ree-bob Just like Landeck posted above and hey it worked well at a time when there was really nothing else to use and over 12 percent nitro was seldom used.

So you see jaka your presumption is, well is just wrong!


Now I do not use dope that much anymore even though I will do an occassional nostalgia project in silkspan or silk but the simple reason is its just to darn expensive anymore and I do use at times up to 40% nitro.

And please note I do and will continue to use rubbin alcohol for thinning epoxie simply because it works, works well and is cheap. And I am actually doing it rather than just chasing down negative threads and posting links.

What does it cost to try, perhaps a few minutes.

EddieC

"I don't even know where to buy old fashioned dope"

Let me help they 'gots' all sorts of good stuff nitrate, nitrate thinner, butyrate, butyrate thinner:

http://www.aircraftspruce.com/menus/...hcoatings.html

John

scale only 4 me

My Feedback: (158)

For small batches I've even used spit,, yes saliva,, epoxy is pretty forgiving

eddieC

My Feedback: (2)

[quote]Let me help they 'gots' all sorts of good stuff nitrate, nitrate thinner, butyrate, butyrate thinner:  [quote]

Well acquainted with AS, a friend of mine knows the owner. I was referring to LHS's, haven't seen nitrate in 20 yrs there.

FlyingGatsby

I've used JohnBuckner's method, and it worked great. I'm not thinning it out to fuel proof a firewall, I made repairs to my vertical find, and put two triangular pieces of basswood on the outside to reinforce it.

skeeter_ca

This method from the West System link above seems like the way to go. I'm going to try it very soon on my SS60 build.


"With wood, the best method of thinning epoxy with heat is to warm the wood and have the resin and hardener at room temperature. Mix the components and apply the mixture to the warm wood surface. Remove the heat source just before the epoxy is applied. When the epoxy mixture comes in contact with the warm wood, it gets warm and its viscosity becomes lower. As the temperature of the wood falls, the thin epoxy is drawn in deeply before it begins to gel. By heating the substrate instead of the components, you get the best of both worlds-low viscosity epoxy on the work surface and longer working time in the mixing pot.

Potential Problems
Thinning epoxy with heat can create problems, however. Warm epoxy cures much more quickly than you may be accustomed to. Have things organized before you mix the resin and hardener and move quickly. Use one of the slower hardeners-206, 207, or 209-to increase the working time.

How warm is warm? You should be able to comfortably touch the substrate or the component containers when they are appropriately warmed-about 115°F maximum. Excessive heat will cause the epoxy to harden too fast, especially in thick applications. Very rapid cure will overheat the epoxy. If smoke rises from the curing epoxy, it is likely the epoxy is damaged and should be replaced."

skeeter