Author Topic: Butyrate dope question (Read 3322 times)

John Fitzgerald · « **on:** December 21, 2011, 06:56:47 PM »

I have noticed the Sig dope products are higher priced than the Brodak dope products, particularly for clear dope.
Is there any significant difference in usability or thickness of the current products? I know the Sig USED to be a lot thicker, so a pint of it would need a lot of thinner and go a lot further than some other products that came already "thinned".

BTW, I found an unopened gallon can of thinner hidden in a cardboard box in my shed a few days ago. So, after Christmas shipping rush, I will likely order some dope products to do my profile F-51 Mustang kit- I do not have any silver dope. I have pretty much decided that the traditional dope route may be best after studying paint compatibility issues the last few weeks, along with the desire to keep it as light as possible. I have not done a doped finish in about ten years. I do remember it stinks quite a lot, and I will have to wait for some warmer days to have the garage door wide open.
Thanks in advance.

Clint Ormosen · « **Reply #1 on:** December 21, 2011, 08:28:31 PM »

Quote from: John Fitzgerald on December 21, 2011, 06:56:47 PM

I have noticed the Sig dope products are higher priced than the Brodak dope products, particularly for clear dope.
Is there any significant difference in usability or thickness of the current products?

I can't comment on the current Sig products, but the current Brodak dope is a bit thinner than what I remember Sig dope being. Not enough to matter, but since you asked........

The thickest dope on the market (that I know of) is the Randolph brand, especially the butyrate clear (like maple syrup). Yes, I know Randolph makes Brodak dope, but it's a little different consistency. Certified dope seems a little thinner, but it might be my imagination.

All are perfectly usable dopes. Just thin them accordingly and remember not to use different thinners on the same plane. You can probably mix the dope brands, but stick with one thinner. I use Randolphs butyrate thinner with good results.

john e. holliday · « **Reply #2 on:** December 22, 2011, 09:27:50 AM »

So far I have not noticed a difference in the thichness of either Brodak or SIG clear butyrate dope. Maybe SIG is using their name and reputation for the higher listed price. I have used both and find I have to thin them quite a bit to be able to brush the clear.

Balsa Butcher · « **Reply #3 on:** December 22, 2011, 09:40:20 AM »

Brodak dries faster, colors have more pigment. Sig is more fuel resistant. I have gone back to Sig because of the fuel resistance issue. Both are usually thinned 50/50 or so before brushing, sometimes more if spraying.

Randy Powell · « **Reply #4 on:** December 22, 2011, 02:25:20 PM »

I buy either Randolph's or Certified in gallons from Aircraft Spruce (which reminds me, I need to order some). The stuff looks like maple syrup when poured. Probably why I buy a gallon of paint and two gallons of thinner.

Bill Little · « **Reply #5 on:** December 22, 2011, 04:11:43 PM »

Hi John,

I use all the different brands but only one thinner in all of them. This includes the Duplicolor *Paint Shop* colors which are in quart cans and a type of altered lacquer to make the EPA happy. I use clear butyrate over it. They only have about 8 colors available, but one is *Performance Silver*. About $22 a quart. The spray cans of Duplicolor lacquer auto touch up paints are compatible, also. My thinner of choice is Dupont 3608S (NOT *VS*).

BIG Bear
AMM

John Fitzgerald · « **Reply #6 on:** December 22, 2011, 04:34:36 PM »

Thanks for the responses. I haven't done a dope job in about 10 years, so did not know if things have changed. Think I will order some from Sig, along with some plywood after the holiday shipping rush clears. Can't get any aircraft grade ply around here any more, even at the hobby store. Only lite ply. I am using mostly the very oily Fox Superfuel, so I need the fuel/oil resistant dope.

John Fitzgerald · « **Reply #7 on:** December 22, 2011, 04:37:25 PM »

Quote from: Ty Marcucci on December 22, 2011, 01:58:09 PM

John, dope does not stink, it has a "unique bouquet". Wasamattau? Youa no like da dope, eh?

If I was a bachelor, I would do the finish right in the house (with ventilation), but the lady of the house doesn't like the "dope bouquet" or any perfume smell for that matter.

Dick Pacini · « **Reply #8 on:** December 22, 2011, 04:43:03 PM »

Just to piggyback on the dope fumes issue...

Years ago, I traveled in my work. I always had a plane with me in the trunk. One week in Toledo, Ohio, I was building a Magician in the motel room. I guess the dope fumes pretty much emptied the adjacent rooms out in the middle of the night.

I was spoken to the next day.

billbyles · « **Reply #9 on:** December 23, 2011, 09:47:55 PM »

Quote from: John Fitzgerald on December 21, 2011, 06:56:47 PM

I have noticed the Sig dope products are higher priced than the Brodak dope products, particularly for clear dope.
Is there any significant difference in usability or thickness of the current products? I know the Sig USED to be a lot thicker, so a pint of it would need a lot of thinner and go a lot further than some other products that came already "thinned".

BTW, I found an unopened gallon can of thinner hidden in a cardboard box in my shed a few days ago. So, after Christmas shipping rush, I will likely order some dope products to do my profile F-51 Mustang kit- I do not have any silver dope. I have pretty much decided that the traditional dope route may be best after studying paint compatibility issues the last few weeks, along with the desire to keep it as light as possible. I have not done a doped finish in about ten years. I do remember it stinks quite a lot, and I will have to wait for some warmer days to have the garage door wide open.
Thanks in advance.

Hi John,

I highly recommend that you stick with butyrate thinner for thinning any butyrate dope. I know that a lot of builders get away with using various types of their favorite lacquer based thinners, but butyrate thinners have solvents in them that assist the flow-out of the dope & provide the right amount of chemical "bite" into the underlying layers for best adhesion. Lacquer thinners work on our models because there is not much surface area to keep wet; many years of professionally restoring, covering, & painting full-scale antique airplanes, WWII warbirds, and modern fabric covered airplanes such as Pitts Specials has made me a believer in using the right thinners for the dope or enamel, or polyurethane.

John Fitzgerald · « **Reply #10 on:** December 24, 2011, 11:48:45 AM »

I was told long ago by a guy who is a professional auto painter and also a modeler that butyrate thinner is virtually the same as PPG DTL16 thinner. I guess it worked for him.

billbyles · « **Reply #11 on:** December 24, 2011, 05:20:54 PM »

Quote from: John Fitzgerald on December 24, 2011, 11:48:45 AM

I was told long ago by a guy who is a professional auto painter and also a modeler that butyrate thinner is virtually the same as PPG DTL16 thinner. I guess it worked for him.

Yeah, I have heard that all kinds of thinners are the "same" as butyrate thinner but over the years I have found it just ain't true. And, "virtually the same" is not necessarily the same; it's his SWAG. Again, the reason that many of these alternative thinners work is because the object we are painting is small enough that they get away with it. Buy your butyrate thinner from Aircraft Spruce & Specialty at about $24 per gallon and you are getting as good or better deal than with the "other" thinners and it is the correct thinner for the butyrate dope. Butyrate thinner is priced right & is so readily available that I just fail to understand why some guys feel the need to be "experimental chemists" in their quest to use other thinners.

larry borden · « **Reply #12 on:** December 24, 2011, 06:34:37 PM »

The only thinner I use now is the Dupont 3608S. I then both nitrate and butyrate and colors. For cleaning spray guns and brushes, I use Acetone. I use Randolph dopes, bothe colors and clear. Brodak crystal clear for final coats.

John Fitzgerald · « **Reply #13 on:** January 02, 2012, 03:03:12 PM »

Thanks for all the responses. I ordered some Sig Lite Coat, Supercoat color, and thinner. I will use the PPG DTL 16 for clean-up.

Howard Rush · « **Reply #14 on:** January 02, 2012, 06:03:28 PM »

Quote from: Clint Ormosen on December 21, 2011, 08:28:31 PM

I use Randolphs butyrate thinner with good results.

Extremely good results, from what I've seen.

John Fitzgerald · « **Reply #15 on:** January 08, 2012, 06:59:17 PM »

I got some Sig dope products. With two coats of Sig sanding sealer (really clear dope with talc), my plane (Sterling F-51 Mustang by Brodak) weighs 11.5 ounces without motor or any hardware except bellcrank, pushrod, and leadouts. The horiz stab, elevator, flaps, and TE are covered and hinged with silver Brodak plastic covering. How much more weight can I expect it to gain from subsequent coats of dope? Planned is one more coat of sanding sealer, one to two coats of clear, one coat of color, then one light coat of clear. As the dope gasses off, will the model lose a couple of ounces? I have built several models before, but until now have not had the means to weigh them as they were under construction.
The wing will be covered with the plastic film.

john e. holliday · « **Reply #16 on:** January 09, 2012, 08:10:07 AM »

Yes you will loose a few grams of weight as time goes on until you start flying. If using electric power should be no weight gain or loss. Now IC you have the build up of oil film over time. A good cleaner helps with that.

Author Topic: Butyrate dope question (Read 3322 times)

John Fitzgerald

Butyrate dope question

Clint Ormosen

Re: Butyrate dope question

john e. holliday

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Balsa Butcher

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Randy Powell

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Bill Little

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John Fitzgerald

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John Fitzgerald

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Dick Pacini

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billbyles

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John Fitzgerald

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billbyles

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larry borden

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John Fitzgerald

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Howard Rush

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John Fitzgerald

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john e. holliday

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