asphaltum test notes

Dies Saturnus

Luna wx 61%v

Prepared four small pieces of scrap metal (copper, brass, bronze220) and coated them with both thick and thin layers of asphaltum varnish from Rio. Prior to coating the pieces were scrubbed with extra fine pumice and scotch-brite pad in a soapy solution and then thoroughly rinsed. They were then wiped down with 99% alcohol to completely degrease.

Asphaltum was applied with a soft-haired brush moistened with mineral spirits to ease in the spreading.  The  varnish had the consistency of honey and adhered very well. The thin layer was as little as I could get away with and still have full coverage, a film. The thicker coating was about 1/64-32″ thick.  Asphaltum thins super-easily with mineral spirits an cleans up well with that too. I did not find it particularly messy but then again I was meticulous in preparing the working space and in application.

The pieces were left to dry in the unheated studio room (probably about 65* average in there) wit no additional heat lamps or other heat sources. Humidity levels were consistent with indoor fall  Oregon levels – fairly high but not steamy. This makes for slow drying.

What I was aiming for was reaching a firm, wax-like consistently that would be firm enough to lay paper with the image on top of it without smearing or sticking and still be soft enough to first do a sketchy tracing with the scribe through the paper. Then the paper would be removed and the complete image scratched through the asphaltum, and the metal placed in an acid bath for etching.

12:05pm (11/13) asphaltum applied, thick and thin samples.

3:05pm thick and thin layers still liquid, line drawn directly with scribe does not hold.

4:25pm very sticky, direct-drawn line holds in all samples but is easily movable

5:25pm firmer w/tacky surface, line holds in thick & thin samples

6:30pm direct line holds, paper sticks to tacky surface on all samples

Wondered if I could powder the surface and then use paper for tracing. Had no powder on hand, ground up gold glittery eyeshadow and used that. Worked on the thin layer, thick layer moved around too much to be useful even on powdered surface.

7:05pm unpowdered paper peelable but still sticks a little on thinner samples, still to sticky for thick ones. Powdered samples work very well, esp thinner ones. Direct scribed lines hold very well. Some “drag” on thicker samples, though.

8:25pm thinner samples very firm and workable with paper both with and w/o powdering, thicker still gummy but surface firm enough to touch *beginning of good, reliable firmness for scribing though using transfer paper*

10:25am(11/14) still firm but flexible

12:05pm firm, takes impressions well, no sticking on thin & powdered samples, thick samples also ok but move & drag somewhat more.

6:35pm similar state as that  of 12:05, best option seems to be lightly powdered thin layer allowed to set up 16-24 hours, powdered at 6-8 hours in

prep for the next piece