Oil Issues

 

Oil Issues

 

Hi David,
 
This may seem to be a very elementary question but what characteristics mark the visual difference between an oil or acrylic painting? If I were to have one of each - side by side - how would I be able to differentiate and tell which was the oil and which was the acrylic - especially if the paintings are 20 - 25 years old.
 
Thank you for your response, Kathy

A.  It is not an elementary question at all Kathy.  In fact it is often hard for experts to tell them apart.  Other times it can be quite simple, depending on the style and techniques used.  It would actually be easier if you had an oil and an acrylic painting side by side so you could compare differences. 

There are many factors involved.  Some things to look for would be yellowish brown oil stains on the back of the canvas where oil may have soaked through. That is a sure give away that the painting was done in oil.  Brush marks are more prominent in oils as well.  Smooth, soft blended tones and edges are a sign that oils have been used.  If there is any yellowing or cracking in the paint film that probably means it is an oil painting. 

Acylic paintings tend to have a more synthetic look.  The paint will be quite hard on an older oil painting whereas acrylic paint is thermoplastic so it will get softer when warm.  If you can dig your nail into the paint and it is not hard, that means it is likely an acrylic piece.

Hope that helps Kathy, thanks for the question.  David

 

Hello David,
 
My name is Linda, I am writing from Toronto, Canada.  I have recently started painting with oils, so please, pardon my ignorance. I am using linseed oil to thin out my paint. I painted the background 1st, but I am finding that it is still not dry after 3 days.  Is this normal? Or am I using too much linseed oil? How do I know when I am using too much or too little? Or is it a factor at all? I would like to know what the general amount of time it takes for a thin layer of oil paint to dry?
 
Thanking you in advance for your co-operation.

Hi linda,

It is not a good idea to thin your paint with linseed oil.  It will drastically slow the drying time.  Because of the excess oil used, subsequent layers will not stick well to this glossy (“fat”) layer either.  The extra oil will also make the paint yellow more as it ages and it may also cause wrinkling.  If you are painting on canvas, more oil will soak through to the fabric and cause it to rot prematurely. 

It is much better to use an oil painting medium to thin your paint.  There are many good quality ones available at the art supply store.  My favorite is called Liquin, made by Winsor & Newton.  Some “fast drying” mediums will even speed up the normal drying time of the paint.  Some colors dry faster than others and the addition of a good quality medium will regulate this as well. 

If you do not want to use a painting medium then you can thin your paint with a solvent (mineral spirits or turpentine) or just apply a very thin pure layer of color.  Don’t use too much solvent either or your paint layer will be too ‘lean’ and loose its flexibility – causing cracking and flaking. 

Have fun painting, David