Cloudy Polyurethane...

[yvan]

I just finished assembling the frames I made for a mobile trolley to carry my printer and decided to apply 3 coats of 50:50 polyurethane/turps before assembling the lot together. The frames are made of 42 x 19mm DAR radiata pine and were sanded from 120 to 320 grit before the 1st coat.

First coat was applied with a brush and was absorbed "immediately"and left to dry 24hrs. I did not sand this first coat.
As an experiment, I applied the second coat with a clean, lint-free pad, to see if the application would be easier than using a brush, and let it dry 24hrs. As I tried to sand that coat, I found it was still tacky and "oily". I had a look at my 50:50 poly/turps mix and noticed it was cloudy.

I can't figure out why it would be cloudy as I used a new can of Cabbot oil-based poly and opened a new bottle of mineral turps (Diggers) to prepare the mix. Could an experienced finisher offer a possible explanation for this?

Not a drama, just curious !!!

Yvan

[q9]

First thought is moisture absorption. Does it go away when stirred?

[PJM16]

I'm not overly experienced, but my first thoughts would be how cool did it get overnight? If it's to cold, I've known poly urethane to simply not set/dry properly.

[yvan]

Thanks G9. Will check & report. Yvan

[yvan]

PJM16, I just had a quick look at the Bureau of Met temperatures for the last 4 nights and the lowest temp was 11.9oC.
So, the temperature inside my workshop would have been a tad higher, say 13-14o. Which could be cold enough to slow down the drying process?

Yvan

[woodPixel]

As G9 says - moisture.

Turps from diggers can be up to 20% water.

This can be overcome by buying IMS from a painting shop... Such as The Paint Place.

Also, many thin light coats are better than a thick one.

How about a few pictures :)

[yvan]

Hell. I would have thought that 20% moisture in the turps would be enough to separate into 2 layers - obviously not!
Will get IMS and prepare a fresh batch!

Pictures...you are now throwing a biiig challenge :). I'll have to visit the FAQ's and have a good read. Will try to accommodate!!

Cheers Yvan

[Christos]

...... I'll have to visit the FAQ's and have a good read. ....

http://www.woodworkforums.com/f36/uploading-photos-attachments-168803

[themage21]

Silly question, isn't IMS metho, not turps? Perhaps there is some solvent confusion going on?

Cloudy would still indicate moisture and tacky after a 13deg night wouldn't be unexpected, but I would think that 20% w/w water in turps would formm a layer unless emulsified.

The other options for cloudy poly in the tin is LOTS of entrained air or your pot is near end of shelf life.

[woodPixel]

Silly question, isn't IMS metho, not turps? Perhaps there is some solvent confusion going on?.

Gak! Of course, how incredibly stupid of me. I wasn't thinking. You are of course right.

100 apologies.

[Big Shed]

Gak! Of course, how incredibly stupid of me. I wasn't thinking. You are of course right.

100 apologies.


This is the main reason I hate the use of acronyms!