Replies

1. 
   nikkiwood | Jun 20, 2005 04:08pm | #1

   There may be some slight chemical difference, but from a functional point of view, paint thinner and mineral spirits are interchangeable.

   Turpentine would also work just fine as a thinner, but I don't use it, but only because I don't like the smell.

   If you want to speed up the drying process, you can substitute naptha for paint thinner/mineral spirits.

   ********************************************************
   "I tend to live in the past because most of my life is there."
   -- Herb Caen (1916-1997)

1. 
   WillGeorge | Jun 21, 2005 09:47pm | #8

   Turpentine reminds me of my visit to Main!

2. 
   HowardAcheson | Jun 20, 2005 07:32pm | #2

   Let me add that it makes no difference which thinner you used when making an oil/varnish mixture.  If you use naphtha, it may dry just slightly faster than using mineral spirits or paint thinner.  I agree that turpentine has no advantages and does have a very pungent odor.

   However, for making a thinned varnish, naphtha will flash off (become tack free) fairly fast.  Standard mineral spirits (if you can get it) is about medium speed and odorless mineral spirits is the slowest.  The latter is a benefit if you are starting off with one of the current "fast dry" poly varnishes.  These have driers added and using naphtha can actually cause the finish to become sticky almost immediately.

   Howie.........
1. 
   Peter36 | Jun 20, 2005 11:15pm | #3

   Thank you Howie. Odourless mineral spirits it is then.  Peter

2. 
   DougF | Jun 21, 2005 04:59pm | #4

   Howie, were does turp fall in the flash rate: medium or slow?  Does turp offer any advantages compared to the other thinners?

   Doug

1. 
   HowardAcheson | Jun 21, 2005 05:44pm | #5

   I don't know the details on turpentine and I haven't used it in 20-30 years.  It used to be a very variable product as each distiller had his own ways.

   I guess you could look it up on google.

   Personally, I know of no place where turpentine would have any advantage.  Petroleum based thinners are what almost all use these days.Howie.........

1. 
   DougF | Jun 21, 2005 05:56pm | #6

   Thanks Howie..  I am trying an oil/varnish formula that uses turp in place of other thinners and I was curious if there might be a reason.  I've applied several coats thusfar and the results are nice - not sure if it is any better than other blends - but not pleasant on the nose.  I'll do some more research.

   Doug

1. 
   DougF | Jun 21, 2005 06:10pm | #7

   All,

   Given the recent threads on oil/poly/varnish, I thought I would post this information regarding turpentine as a thinner with linseed oil.

   "In the manufacture of varnish pure gum spirits has a variety of roles. It is a solvent, a flowing agent, and a drier.

   As a solvent in linseed oil varnish turpentine is unique. Turpentine cannot be considered a solvent in the same way that alcohol dissolves shellac or water dissolves salt. These are solutions where a specific quantity of solid combines with the solvent to form a diluted copy of itself. Evaporate the solvent and the solid is left unaltered. Linseed oil is highly solvent in turpentine at room temperature. Once combined however, the turpentine and linseed oil cannot be separated by distillation into the original components. Turpentine and linseed oil are mutually soluble. Some resins are directly soluble in turpentine. Some resins require processing to make them soluble. Natural varnish resins are compounds. A mixture of turpentine and resin will contain dissolved and undissolved elements suspended in the mixture. Resin solutions are colloidal in nature and once established will not break down into their original components. Natural varnish resins and turpentine are mutually soluble. In the varnish making process turpentine is added to the resin and oil to promote the mutual solubility of the three elements.

   As a flowing agent turpentine is superior to other solvents. If a linseed oil varnish is made in the same way, except mineral spirits is used instead of turpentine, and samples of each are brushed on the same surface, the brush marks will flow out of the turpentine varnish first and most completely. As the varnish film cures mineral spirits will evaporate completely. Turpentine never completely evaporates. A small percentage remains in the varnish as an elastic resinous substance.

   Turpentine acts as a drier in linseed oil varnish. When pure turpentine is exposed to the atmosphere at room temperature it begins to thicken and gain molecular weight. It absorbs oxygen from the air faster and more efficiently than linseed oil. In varnish it passes oxygen from the air to the oleo-resinous compound."

2. 
   byhammerandhand | Jun 25, 2005 01:36am | #9

   The following is extracted from FWW #151 from a Jeff Jewitt article:

   Oil based finishes

   Thinner

   Drying time

   Comments

   Kerosene

   Slow

   Retarder

   Odorless mineral spirits

   Slow

   Retarder

   Mineral spirits / paint thinner

   Medium

   Changes viscosity without adversely affecting drying time

   Pure gum spirit turpentine

   Medium

   Higher prices, variable quality

   Xylene

   Medium fast

   Best for conversion varnishes

   VM&P Naphtha

   Fast

   Best for fast evaporation. Spraying in cold weather, vertical surfaces, or to make wiping varnishes

   Toluene

   Fast

   Strong odor, naphtha preferable

   Acetone (Ketone)

   Fast

   For spraying thick coats, may wrinkle previous coats