West System

[catbuilder]

Hi All

I use West System Epoxy, I have a question in regards to dewaxing it when cured. Can you use the likes of actone or epoxy thinners to clean it off before sanding so as to not waste a heap of sandpaper. I think I heard of using water and steel wool or jex pads, but I don't want to use water.

Regards

Matt

[Boatmik]

Hi All

I use West System Epoxy, I have a question in regards to dewaxing it when cured. Can you use the likes of actone or epoxy thinners to clean it off before sanding so as to not waste a heap of sandpaper. I think I heard of using water and steel wool or jex pads, but I don't want to use water.

Regards

Matt

Howdy Matt, solvents don't work - ever tried to dissolve salt in a solvent - nothing happens - but the results of salt in water are instant.

Same with the wax - it dissolves readily in water.

I think the WEST people have moved from their original solution of adding some cloudy ammonia to water and now suggest just using water and a scotchbrite.

Ring up Adhesive Technologies in QLD and ask them - they will give the best and most current advice.

They do have a low waxing mix of epoxy - I think you have to pay extra for it though. The bote cote has this in the standard mix. There are starting to be others that have low waxing resins available - some at a bit of extra cost others in their standard ranges.

MIK



Michael

[bitingmidge]

I may be wrong, but I thought the "wax" was actually an amine bloom, and the ammonia is a solvent for same? Water works, but with cloudy ammonia it works better.

Boatcote don't (or at least didn't) use an amine based hardener, hence no bloom.

Last time I said something like that I was flamed by a chemist... but at least I got the info out! :wink:

cheers,

P

[Boatmik]

Howdy Midge,

Amine Bloom - yes. I don't know enough about the chemistry, but amines are related to ammonia and Bote Cote too has hardener with a little bit of an ammonia smell - so it is not without amines. What role they play in the cure - I know nothing about except the hardener changes the PH to alkaline and amines are usually alkaline.

A brief reading of the new edition of "The Gougeon Brothers on Boat Construction" - which has always been the single most useful text for epoxy/timber boatbuilding - shows that after years of suggesting cloudy ammonia and water, WEST say just to use water and a scourer now. The issue is contamination of the surface and they also suggest that clean water works just as well.

The issue seems to be that using water alone reduces the risk for subsequent processes.

I haven't read enough to get the exact info.

Best wishes
Michael

[Daddles]

See, if you stuck with tried and true traditional methods like tar and wooden pegs, you wouldn't have these issues.

Richard

[bitingmidge]

See, if you stuck with tried and true traditional methods like tar and wooden pegs, you wouldn't have these issues.

Cloudy ammonia works perfectly well on tar too. I think it's the active ingredient in that ancient remedy MFKL as well!

If you don't believe me, dip your hand in some tar, and have a go! :D

Cheers,

P
:D

[Boatmik]

If feeling particularly confident you could also do more than just your hand!

Richard - now where did I leave that barrel of feathers - I'll let you have it?

[Wombat200]

All epoxies can suffer from amine blush - although the better quality boat building resins suffer from it alot less. Having used WEST & Bote Cote, I have had the problem with both but only on rare occasions. Using cheaper laminating resins (non-marine use) is a sure-fire way to get it, but then it's often not a real problem.

I always used warm soapy water & scotch-brite pads to clean off......

[Lewy the Fly]

Having almost completed the sheathing on my paulownia experiment ( I'll post photos again shortly) I have found temperature and humidity effect the amount of wax ( No hard data just seems that way) also 207 hardner seems to have less wax. I washed down with water and cloudy ammonia and scrubbed with a scouring pad on the random orbit sander in the begining, however I found that with good quality sand paper clogging wasnt a problem. I use Sunmight Film discs on a 6" random orbit air sander with dust extraction.

Regards



Lewy

[hairymick]

G'day Guys,

I now use West Systems exclusively. I use the 105 resin and 207 special hardener and have had absolutely no ammine blush in any of my builds.

Beautiful stuff to use.

[Mattkk]

I found that using water and "wet and dry" sandpaper (v fine grit) worked a treat.

[Boatmik]

Water and wet and dry can be OK - just don't let the water dry again on the surface as it will drop the amine back where it came from!!!

MIK