Bitumen and Asphalt, dentistry HF and assorted questions.

[Julio Cesar Germano]

Hello everyone and brace yourselves!

Are bitumen and asphalt varnish the same thing?
I know bitumen and asphalt are derived from the same petrochemical gooey stuff, but I thought it best to check before buying it.

I found a dentistry supply shop that keeps and sells low concentration HF without having to go about the fuss of finding a chemical engineer/dentist to buy it for me. (Obs.: Concentrated HF is army regulated here in Brazil, tough to get a permit).
Anybody knows if it's actually useful for etching?

I also found, finally (!!), an art and restoration store that sells gold size (LeFranc's 3hr) and was considering to buy a bottle of it. I've seen the brand's name all over the forum with mixed reviews as to the old and new formulas. Is it still good? Good for beginners? Can it be worked with a brush? Used on screen printing?

Another question edited in:
I tried an ink from the brand Tamiya, it's sort of the staple brand for modelism painting, and though it's got some good pigmentation and adhering nice to the glass, I can't get it to brush consistency, when I add turpentine to thin it a little bit, it goes all gooey. Sort of like a rubbery stickiness creating strands inside the brush hair and making a mess...
Anybody has a guess wether it's the paint, the turps or the painter?

I bought me a pack of 500 copper leaves and am eager to waste them away.
I hope the gatling-gun of questions is allowed.

Best of luck in all endeavours!
Sincerely,

JC

[Lee Littlewood]

Julio,

on the LeFranc 3 hour size:
It has changed some. I never used the old stuff (yellow label, and I think for awhile a mauve label), but the new version (white label) seems to gild fine. Just one thing - DON'T MIX ANYTHING WITH IT! You can't mix it with the LeFranc slow size, or with Rolco quick, or anything. So says Mark at Sepp leaf, and I believe him. He even suggests using UTC colors to tint it, rather than a drop of 1Shot.
As a point of interest, he finds 1Shot fast size ready in 1 hour, Rolco quick size ready in 2 hours, and LeFranc 3 hour ready in 3 hours. This is a picture framer, in New York, so adjust for your own conditions. I think that framers put size on much thinner than signpainters do - they don't have to make letters, so they can go back in with a dry brush and pull wet size off the surface. My friend Nancy Thorn says that she spends twice as long removing size as she does laying it down. But the general progression of timing seems right to me: 1Shot faster than Letterhead Supply faster than Rolco faster than LeFranc. The LeFranc 12 hour is still the best thing since plastic all-day lollipops.

on asphalt/bitumen - isn't the question not bitumen vs. asphalt, but whether it is a "varnish"? I remember there was a discussion on this some years ago, but i've lost the thread..

the Tamiya ink - does it need a hotter thinner than turps? Maybe naptha? It sounds like a classic 'wrong solvent' reaction - the paint gets all snotty textured (like what happened to me with LeFranc 3 hr and Rolco) and gums up in the brush. Are you sure it is not a water soluble ink?

keep on keeping on, something has to work....

[BradG]

I think Lee's onto something. I read your post before, Cesar, but I didn't see Tamiya in it, or I would have been more curious as I know Tamiya from model building.

Tamiya paints are all acrylic, I think, and water-soluble, so if you put turps in it they would get weird indeed. They have their own thinner that you can use, if you want to still use that.

I would do some tests to see how well it holds up compared to other paints/inks like One Shot or Nazdar ink.

[Julio Cesar Germano]

Hey there,

BradG, I edited the question about the Tamiya paints a little later. I was hoping to use the tamiya because it was the only decent paint I found around here... There's no 1-shot retailer in the country and because it's flammable, most online stores can't deliver it from overseas.

I'll be making my first test run with the LeFranc size and copper leaf this weekend, will be posting whatever results around here.
Should be fun.

Thank you for the advice!

Sincerely,

JC