Way too Weird!

Well, for 55 years I've done this model thing. I've used Berryloid, Cooper, Randolpfs, Sig, Testor's, Brodak's, Aerogloss, Co-loidal-Ac, homebrew, furniture lacquer and any other number of stuff. I've covered with silk, tissue, silkspan, bamboo paper, gift wrap, toilet paper, condensor paper and all other sorts of papers, fabrics and plastic films. Last night, after all that I came across a mystery that likes of which I've never seen. Now I mix all kinds of stuff doing finishes, some of you may remember my Jetco Sabre done in Brodak's and thinnered with common department store variety thinner. Well, last night I was helping my grandson with a P-30 rubber model, he got it all framed up and sanded, and applied 3 coats of the same Brodak clear thinned with Meijer's off the shelf lacquer thinner. Got it to a nice mild gloss indicating there was enough dope on the wood to adhere the tissue. I use thinner when I cover with tissue. I brush it on the tissue, it softens the dope and it sticks, I've done this for years. So, we cut the first piece, tack down the end and go to pull it snug and it falls off! Try again, try some thinned dope instead, it falls off. So I take the fuselage and get a drop of thinner on my finger and touch it to the wood. Nothing!! More, I rub, nothing, LACQURE THINNER WON'T TOUCH THE DOPE, NOT EVEN SLIGHTLY!! Well, I tell my grandson I suspect the humidity (very humid last night) though I really don't have a clue. Went down this morning and tried again, the dope totally resists softening with thinner. Last resort, acetone. I get some out, and thankfully, it works, so we'll get it covered today and trimmed for next week's contest in Muncie.

Like I said, I've mixed all kinds of stuff, and this combination is not new, I've been doing it for a number of years. Its like something catylized the dope and made it impervious to its own solvent. Will I continue mixing products, OF COURSE I will! Being the cheapskate I am, I have to, but this one will go down in the memory bank as a real mystery, after 55 odd years, an new mystery

Randy Ryan <><
AMA 8500
SAM 36
BO all my own M's

Randy,

The paint companies keep messing around with formulas to keep environmentalist at bay for a while. I'll bet Sig's formulation has changed at least somewhat over the last 20 years.

Jim Pollock

I've seen the same thing with Name-brand spray paints. Some for the good, some bad. Try and find a good lacuer anymore...

>Well, for 55 years I've done this model thing. I've used
>Berryloid, Cooper, Randolpfs, Sig, Testor's, Brodak's,
>Aerogloss, Co-loidal-Ac, homebrew, furniture lacquer and any
>other number of stuff. I've covered with silk, tissue,
>silkspan, bamboo paper, gift wrap, toilet paper, condensor
>paper and all other sorts of papers, fabrics and plastic
>films. Last night, after all that I came across a mystery that
>likes of which I've never seen. Now I mix all kinds of stuff
>doing finishes, some of you may remember my Jetco Sabre done
>in Brodak's and thinnered with common department store variety
>thinner. Well, last night I was helping my grandson with a
>P-30 rubber model, he got it all framed up and sanded, and
>applied 3 coats of the same Brodak clear thinned with Meijer's
>off the shelf lacquer thinner. Got it to a nice mild gloss
>indicating there was enough dope on the wood to adhere the
>tissue. I use thinner when I cover with tissue. I brush it on
>the tissue, it softens the dope and it sticks, I've done this
>for years. So, we cut the first piece, tack down the end and
>go to pull it snug and it falls off! Try again, try some
>thinned dope instead, it falls off. So I take the fuselage and
>get a drop of thinner on my finger and touch it to the wood.
>Nothing!! More, I rub, nothing, LACQURE THINNER WON'T TOUCH
>THE DOPE, NOT EVEN SLIGHTLY!! Well, I tell my grandson I
>suspect the humidity (very humid last night) though I really
>don't have a clue. Went down this morning and tried again, the
>dope totally resists softening with thinner. Last resort,
>acetone. I get some out, and thankfully, it works, so we'll
>get it covered today and trimmed for next week's contest in
>Muncie.
>
>Like I said, I've mixed all kinds of stuff, and this
>combination is not new, I've been doing it for a number of
>years. Its like something catylized the dope and made it
>impervious to its own solvent. Will I continue mixing
>products, OF COURSE I will! Being the cheapskate I am, I have
>to, but this one will go down in the memory bank as a real
>mystery, after 55 odd years, an new mystery
>
>Randy Ryan <><
>AMA 8500
>SAM 36
>BO all my own M's

Hi Randy,

What you probably got is the VOC compliant lacquer thinner which will not work with dope...it does not dissolve the dope even slightly. If you pour it into a container of dope it will make goo out of the dope but will not mix. Dupont calls their non-VOC compliant mid-temp lacquer thinner 3608S; the new VOC compliant thinner is called V3608S...it is the stuff that will not mix with dope.

If you need a solvent that evaporates more slowly than acetone you can use Methyl Ethyl Ketone (MEK) which has about 1/3 the evaporation rate of acetone. MEK is also available at hardware stores, Lowes, etc.

>>Well, for 55 years I've done this model thing. I've used
>>Berryloid, Cooper, Randolpfs, Sig, Testor's, Brodak's,
>>Aerogloss, Co-loidal-Ac, homebrew, furniture lacquer and
>any
>>other number of stuff. I've covered with silk, tissue,
>>silkspan, bamboo paper, gift wrap, toilet paper,
>condensor
>>paper and all other sorts of papers, fabrics and plastic
>>films. Last night, after all that I came across a mystery
>that
>>likes of which I've never seen. Now I mix all kinds of
>stuff
>>doing finishes, some of you may remember my Jetco Sabre
>done
>>in Brodak's and thinnered with common department store
>variety
>>thinner. Well, last night I was helping my grandson with
>a
>>P-30 rubber model, he got it all framed up and sanded,
>and
>>applied 3 coats of the same Brodak clear thinned with
>Meijer's
>>off the shelf lacquer thinner. Got it to a nice mild
>gloss
>>indicating there was enough dope on the wood to adhere
>the
>>tissue. I use thinner when I cover with tissue. I brush it
>on
>>the tissue, it softens the dope and it sticks, I've done
>this
>>for years. So, we cut the first piece, tack down the end
>and
>>go to pull it snug and it falls off! Try again, try some
>>thinned dope instead, it falls off. So I take the fuselage
>and
>>get a drop of thinner on my finger and touch it to the
>wood.
>>Nothing!! More, I rub, nothing, LACQURE THINNER WON'T
>TOUCH
>>THE DOPE, NOT EVEN SLIGHTLY!! Well, I tell my grandson I
>>suspect the humidity (very humid last night) though I
>really
>>don't have a clue. Went down this morning and tried again,
>the
>>dope totally resists softening with thinner. Last resort,
>>acetone. I get some out, and thankfully, it works, so
>we'll
>>get it covered today and trimmed for next week's contest
>in
>>Muncie.
>>
>>Like I said, I've mixed all kinds of stuff, and this
>>combination is not new, I've been doing it for a number
>of
>>years. Its like something catylized the dope and made it
>>impervious to its own solvent. Will I continue mixing
>>products, OF COURSE I will! Being the cheapskate I am, I
>have
>>to, but this one will go down in the memory bank as a
>real
>>mystery, after 55 odd years, an new mystery
>>
>>Randy Ryan <><
>>AMA 8500
>>SAM 36
>>BO all my own M's
>
>Hi Randy,
>
>What you probably got is the VOC compliant lacquer thinner
>which will not work with dope...it does not dissolve the dope
>even slightly. If you pour it into a container of dope it
>will make goo out of the dope but will not mix. Dupont calls
>their non-VOC compliant mid-temp lacquer thinner 3608S; the
>new VOC compliant thinner is called V3608S...it is the stuff
>that will not mix with dope.
>
>If you need a solvent that evaporates more slowly than acetone
>you can use Methyl Ethyl Ketone (MEK) which has about 1/3 the
>evaporation rate of acetone. MEK is also available at
>hardware stores, Lowes, etc.
>
>

Bill,

I don't think you read the whole post, I've been doing this using the same products for years, as a mtter of fact, the clear we used was some of the same batch I used on the Sabre. I'm not dealing with unknowns, its the same, I mean from the same containers, I've been using.

Randy Ryan <><
AMA 8500
SAM 36
BO all my own M's

>Bill,
>
>I don't think you read the whole post, I've been doing this
>using the same products for years, as a mtter of fact, the
>clear we used was some of the same batch I used on the Sabre.
>I'm not dealing with unknowns, its the same, I mean from the
>same containers, I've been using.
>
>Randy Ryan <><
>AMA 8500
>SAM 36
>BO all my own M's

Well Randy, as a matter of fact I did read your whole post and in it you did not state what you stated above: "I'm not dealing with unknowns, its the same, I mean from the
same containers, I've been using."

In your post you stated "...applied 3 coats of the same Brodak clear thinned with Meijer's off the shelf lacquer thinner." I took that to mean that you used the same kind of dope (Brodak clear) not necessarily the exact same batch, and the same kind of thinner (Meijer's). What you meant to communicate was not necessarily how it came out.

That being said, was the thinner that you applied to stick the tissue to the airframe from "the exact same can and batch" that you used before or did you buy some more of the same brand? The manufacturers do not always let us know that they are changing the forumulae when they have to change to comply with VOC requirements; they seem to think that "everybody should know that the change was required by law so why would we have to tell them?"

If nothing at all has changed with the materials you used then it pretty much has to be the way you are doing it. Presuming that the products were all from the same containers and batches that you used before when it worked then it isn't the materials. Even if some of the thinner that was in the Brodak clear had evaporated (which would be normal) it won't change the characteristics of the clear. You can just add more of thinner to reduce the viscosity and go from there. Dope does not develop the characteristic of being "catalyzed" just from sitting around for awhile.

Since it worked before with "Meijer's" thinner, and it worked with acetone this time it would seem like you may have gotten a new batch of lacquer thinner that is VOC compliant and will not dissolve the dope. Acetone, MEK and toluene are the volatile solvents that are in the old lacquer thinner which will dissolve the dope; other solvents in the lacquer thinner are primarily there to adjust the drying speed of the thinner such as isobutyl alcohol, ethyl acetate, etc. and do not, by themselves, do a very fast job of dissolving the dope. The new VOC compliant thinners don't have the Acetone, MEK, and toluene and the formulae of the paints in which they were used have been changed to accommodate this.

Bill,

I apologize, I guess I wasn't all that clear.

Yes, all the same stuff, same batch etc, and the same method I've used since I was 20, this will remain a mystery I'm afraid, the only thing I can think of is that the humidity somehow had an effect though its never done it before, its the only thing different.

Randy Ryan <><
AMA 8500
SAM 36
BO all my own M's

As I've said, even when you are following manufacturer's exact directions using known compatible products, sometimes thing just go heck for no reason. Painting is still more art than science.