Vallejo Satin Varnish?

[Guest]

Thanks guys, always good to learn something new.All the polyurethanes I have had experience with were always oil based, which are not compatible with anything water based.

Just proves to myself, that since I had to retire from my trade I have lost touch with paint technology.

I retract my post unreservedly!

Gregg

Had the same problem Gregg.

Working in architecture found that building practice has changed dramatically in 10 years. Some things I would not have even contemplated. Would not wish to revisit. Some cemented in traditional practices have been just tossed out of the window as irrelevant and also incorrect.

Laurie

[stona]

Thanks guys, always good to learn something new.All the polyurethanes I have had experience with were always oil based,

Gregg

Gregg as an ex-chemist I'm not entirely sure why Vallejo is using the word 'polyurethane' in what they then seem to describe as an acrylic varnish. I don't see how genuine polyurethanes, as I understand them chemically, can be water soluble either. Times move on but I don't think that the laws of physics change so quickly.

I could be wrong too

Steve

[flyjoe180]

I know from recent experience that many 'enamels' and 'polyurethane' paints and varnishes used in houses are now water based. I suppose that same technology flows on to model paints and other art forms too. All good but I hope they don't touch my model oil based enamel range.

[ojays]

I think over the years the terms Acrylic, Enamel, Polyurethane, Cellulose etc., have all been bastardized (sorry)

When learning about paints and their make ups as an apprentice, it was easy to remember which could be thinned or extended, and what was the correct medium to do this, and which could be applied over which safely

For example, the history of 'ACRYLIC' paints used on (mainly) American domestic vehicles in the late 40's through to 70's, was of interest to us aviation fans.

The acrylic used to manufacture aircraft canopies/windows etc,. was at an abundance immediately post war, and going to waste.

Someone (whose name I now forget) worked out that mixed with certain pigments and other chemicals, this medium could be used as a coating capable of protecting the surface it was applied to, at the same time as having a pleasing appearance, then known as 'ACRYLIC COATING' or 'LACQUER'

The American automotive industry was starting to accelerate post war, and saw this as the perfect medium to coat their huge, gas guzzling motors.

We here in the UK during the 40's, were still using oil based paints (ENAMELS) also known as (COACH PAINT) on our vehicles, gradually moving over to CELLULOSE based products, (who remembers BRUSHING BELCO)

.

Here was where the fun began for us automotive painters, and where we learnt the hard way, the incompatibility of coatings.

You could apply ACRYLIC over CELLULOSE (no reaction) You could apply ENAMEL over CELLULOSE (no reaction) You could apply ENAMEL over ACRYLIC (no reaction)

Apply CELLULOSE over ACRYLIC, ( stand back and watch the fun) not. Immediate reaction, pickling/cracking/crazing or reaction as the CELLULOSE coating dried.

Apply CELLULOSE over ENAMEL, exactly same reaction as CELLULOSE over ACRYLIC.

POLYURETHANE was a term we used for plastic based coatings, that gave a very high gloss (but some would say it looked too plasticky) and was found to be a problem to repair, if the surface was damaged. Second coating was a no no, it would react with itself if not recoated in a certain time period,(cracking/crazing) It also required to be baked to fully cure it, or left for 24 hrs.

We then moved onto 2 COMPONENT (2K) paint systems during the late 70's early 80's. Excellent gloss from the gun with minimal post paint buffing/polishing required.

However these were full of isocyanates and other Cancer/Asthma producing products, that were killing off us painters.

Now we come to modern vehicle Paint Coatings, which because of so called environmental reasoning, have to be 'WATER BASED'

The fact that most of the mediums used prior to applying the (water based colour) and the finish Clear Top Coat, now called 'LACQUER,' are still full of undesirable products seem to have been missed somewhere.

Now getting back to my original point, the messing about with the names for the different paints/mediums.

LACQUER is now a clear medium, ACRYLIC is now a water based medium, ENAMEL seems to be the only one that has retained it's original medium.

However some oil based 'GLOSS' paints will react when over coated with ENAMEL.!!!!!!!!!!!

I haven't included the specialist paints such as POWDER COATING, HAMMERITE, CRACKLE, VREEBLE, COBWEB, and too many more to mention.

Most people just see paint as, well paint!

Gregg

[stona]

The polyurethanes I was familiar with thirty years ago were not water soluble but I've been doing a bit of googling and it seems that water soluble ones have been developed. I don't know how recently this was, the first article I read about it was in a scientific journal (the imaginatively entitled 'Journal of Applied Polymer Science') published in 2004. Amazingly I still understood nearly all of it

Another article, dated 1992, in the even more imaginatively named 'European Polymer Journal' confirmed which polyurethanes are water soluble and went into a load of maths relating to solubility which I didn't understand and probably wouldn't have thirty years ago.

After this I was losing the will to live and decided to end my new found scientific career and get back to spraying my Corsair.....with oil based enamels!

Cheers

Steve

[Guest]

Brushing Belco. I remember it well Gregg. Little tin pots.

Smelly. Most paints were compared to know. Virtually dried as the brush left the pot.

Painted my BSA Bantam with it top to tail. But it was an awful paint at least for me. Remember my father looking at the bike and saying to me "you have made a right mess of that". Jolly unfair I had spent hours and many pots of Belco.

Tried I suppose it must have been a cheap airbrush and that worked a little better.

The great paint in those days, as emulsion paint was just working its very expensive way onto the market, was distemper. You had to be a good painter to get a good coverage. I remember my father putting coat upon coat until satisfied. After years of putting the stuff on it started to peel and in cases just fall off. Then it was a matter of scraping the whole ceiling to the bare plaster. Then some of that came away with the distemper. What a mess.

Laurie

[ojays]

The polyurethanes I was familiar with thirty years ago were not water soluble but I've been doing a bit of googling and it seems that water soluble ones have been developed. I don't know how recently this was, the first article I read about it was in a scientific journal (the imaginatively entitled 'Journal of Applied Polymer Science') published in 2004. Amazingly I still understood nearly all of it Another article, dated 1992, in the even more imaginatively named 'European Polymer Journal' confirmed which polyurethanes are water soluble and went into a load of maths relating to solubility which I didn't understand and probably wouldn't have thirty years ago.

After this I was losing the will to live and decided to end my new found scientific career and get back to spraying my Corsair.....with oil based enamels!

Cheers

Steve

Bet you wish you still had that Corsair, not many left now and worth a mint.

Remember well rebuilding the bottom end of one of these in the early 70's.

Gregg

[ojays]

Brushing Belco. I remember it well Gregg. Little tin pots.Smelly. Most paints were compared to know. Virtually dried as the brush left the pot.

Painted my BSA Bantam with it top to tail. But it was an awful paint at least for me. Remember my father looking at the bike and saying to me "you have made a right mess of that". Jolly unfair I had spent hours and many pots of Belco.

Tried I suppose it must have been a cheap airbrush and that worked a little better.

The great paint in those days, as emulsion paint was just working its very expensive way onto the market, was distemper. You had to be a good painter to get a good coverage. I remember my father putting coat upon coat until satisfied. After years of putting the stuff on it started to peel and in cases just fall off. Then it was a matter of scraping the whole ceiling to the bare plaster. Then some of that came away with the distemper. What a mess.

Laurie

Another that some may be old enough to remember 'SNOWCEM' A self sacrificial water based white (distemper type) paint.

It shed its outer coating to (supposedly) keep its clean appearance.

Under no circumstance lean against it, unless you like the looking like the ghost look!

Gregg