Some PolyU Questions again.

I have read one con of PolyU from some sites where they compare it to different finishes like varnish, lacquer, etc is it's too soft to Polish to a High Gloss.

I'm not sure what this means really? Maybe its in a short time period? I have buffed & polished PolyU by hand with auto compounds & polishes to a pretty decent high gloss waiting a week or two after the coat was applied. Is this not an appropriate thing, as it may open the pores of the finish & be less durable?


Some sites say the oil based PolyU (I assume the one that requires turps to wash off) eventually turns a bit yellow. Don't know if this is true its been a few years & some stuff I have looks the same as it did from day one.


BTW I'm using the canned PolyU & do not thin, just apply by brush

thanks.

poly u never goes off hard .... ever ..... it is a plastic and can not ever achieve the crisp, hard, crystaline state that some other finishes will , not even in a two pack.

Pretty much all oil bassed, hydrocarbon thinned finishes ..... those you will thin with turps have some amount of yellow or brown tint in them, this is simply unavoidable ...... pretty much all of them will get more yellow or brown over time with exposure to light ...... this to is pretty much unavoidable in this family of finishes ....... some of these finishes contain UV inhibiters, but this only slows the inevitable.

Poly U will always have some level of milkyness or opacity, this too in unavoidable due to the type of resins these finishes are built on ..... this milkiness is often not apparant because the brown/ yellow tint masks it.
Some simply cant see it, because they know no different, but when you see timbers with realy bright grain and figure, with lots of light reflected from within the timber .... then finished with poly U compared with one of the optically better finishes it is dogs balls obvious.


If you want something that gives a clear, opticly bright, high gloss finish, you pretty much have to look at an alcohol bassed finish. .... and a finish where crystaline resin is disolved

The oldest is is Shelac ..... or as I refeer to it ... beetle .

Pretty much all the modern high quality finishes came down to alcohol ..... their thinner many have many other solvents, but but some how somewhere it comes down to alcohol and alcahol derived solvents ..... and that includes nitro laquer and its derivatives and pretty much all the automotive finishes other than enamel.

Oh and if ya not thinning ya polly U, and using it straight from the can .... ya making life hard for ya self.

cheers

Soundman may I beg to differ...in a nice way. One can achieve a gloss look with a natural oil. In particular the Linn Bathroom Furniture oil give quite a varnished gloss look but is based on Linseed oil. By buffing in-between coats too, one can add to the sheen level.
Regards

Quote:

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Originally Posted by soundman

poly u never goes off hard .... ever ..... it is a plastic and can not ever achieve the crisp, hard, crystaline state that some other finishes will , not even in a two pack.

Pretty much all oil bassed, hydrocarbon thinned finishes ..... those you will thin with turps have some amount of yellow or brown tint in them, this is simply unavoidable ...... pretty much all of them will get more yellow or brown over time with exposure to light ...... this to is pretty much unavoidable in this family of finishes ....... some of these finishes contain UV inhibiters, but this only slows the inevitable.

Poly U will always have some level of milkyness or opacity, this too in unavoidable due to the type of resins these finishes are built on ..... this milkiness is often not apparant because the brown/ yellow tint masks it.
Some simply cant see it, because they know no different, but when you see timbers with realy bright grain and figure, with lots of light reflected from within the timber .... then finished with poly U compared with one of the optically better finishes it is dogs balls obvious.


If you want something that gives a clear, opticly bright, high gloss finish, you pretty much have to look at an alcohol bassed finish. .... and a finish where crystaline resin is disolved

The oldest is is Shelac ..... or as I refeer to it ... beetle .

Pretty much all the modern high quality finishes came down to alcohol ..... their thinner many have many other solvents, but but some how somewhere it comes down to alcohol and alcahol derived solvents ..... and that includes nitro laquer and its derivatives and pretty much all the automotive finishes other than enamel.

Oh and if ya not thinning ya polly U, and using it straight from the can .... ya making life hard for ya self.

cheers

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I appreciate your response.
Reading this: https://en.wikipedia.org/wiki/Wood_finishing

The wiki on finishes says that oil based PolyU cant be buffed to a high gloss, I don't know what this means? As my finish is very hard & can be buffed automotive style to a pretty decent gloss. Although its more the film itself that is gloss & acts to hide the natural wood) The wiki says the waterbased version can be buffed to extreme gloss. I might try this out on a sample piece. I know they wont be as rock hard as the finishes you mentioned. Also twopac seems to be very hard & durable for outdoors in uv & it's pretty simple to apply. I read up on some piano finishes & they seem to age & yellow & dull in gloss from some comments. So I was kind of turned off.

cheers

what product sales litriture and wiki says are one thing reality is another.

remember too a lot of people will not have seen a realy high optical quality finish to compare the muddy milky polyeurathane to

Quote:

---

Originally Posted by soundman

poly u never goes off hard .... ever ..... it is a plastic and can not ever achieve the crisp, hard, crystaline state that some other finishes will , not even in a two pack.

Pretty much all oil bassed, hydrocarbon thinned finishes ..... those you will thin with turps have some amount of yellow or brown tint in them, this is simply unavoidable ...... pretty much all of them will get more yellow or brown over time with exposure to light ...... this to is pretty much unavoidable in this family of finishes ....... some of these finishes contain UV inhibiters, but this only slows the inevitable.

Poly U will always have some level of milkyness or opacity, this too in unavoidable due to the type of resins these finishes are built on ..... this milkiness is often not apparant because the brown/ yellow tint masks it.
Some simply cant see it, because they know no different, but when you see timbers with realy bright grain and figure, with lots of light reflected from within the timber .... then finished with poly U compared with one of the optically better finishes it is dogs balls obvious.


If you want something that gives a clear, opticly bright, high gloss finish, you pretty much have to look at an alcohol bassed finish. .... and a finish where crystaline resin is disolved

The oldest is is Shelac ..... or as I refeer to it ... beetle .

Pretty much all the modern high quality finishes came down to alcohol ..... their thinner many have many other solvents, but but some how somewhere it comes down to alcohol and alcahol derived solvents ..... and that includes nitro laquer and its derivatives and pretty much all the automotive finishes other than enamel.

Oh and if ya not thinning ya polly U, and using it straight from the can .... ya making life hard for ya self.

cheers

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Thinking about this again, Is a 2 pack Poly as hard as typical auto 2pac Lacquer? Can it have the same high gloss?

I don't think there are any alcohol based hard high gloss finish's that are durable against rubbing & chemicals like Poly or 2pack or that don't yellow. They seem more suited for fine furniture where regular upkeep is required.

Looking for crystaline resin finishes that are very durable like polyU.

thanks

The whole point of two pack poly is that it is flexible and resilient.

There are other two pack finishes that are hard and clear but much less flexible ..... but there in lies the problem .... because they are less flexible they crack on material with movement
This is why most two pack finished kitchens and the like are made from manufactured board such as MDF.

The thing you gota remember is ...... there IS NO free lunch.

IF the finish is crystal clear and water white, it will be UV suceptable ..... if it does not yellow it will break down otherwise.

There simply is no way to produce UV durability with out introducing colour or opacity at at least some level.

Likewise a high opticly clear finish will by nature be be hard and crystaline in nature..... it's a matter of atomic physics

Look at any lense material ....... The optical clarity will be related in some way to hardness ...... soft plastics will very rarely have the optical performance of even closely related harder plastics.

If you want to introduce strength and durability to a resin, the easiest way to do that is to introduce solids ..... in fact if you are buying opaque paints and glues, you should be looking at the solids content as an indicator of quality.

Here lies the problem with clear finishes, introducing solids to increase durability, increases opacity ......... I know of no case where a clear finish will perform anywhere near as well, ias for durability and UV resistance as an opaque product bassed on the same resin system.

I little observation in plastics will show you that even different colours of exactly the same plastic perform differently .... some colours will be harder some will be more flexible ..... it depends on what has been used to colour the product. ..... different colours will definitely be more durable than others .... this even extends to inks for the same reason ...... Black will pretty much always be the hardest and most UV durable.

Yes there are some compromise products that produce very good results ..... but hell they are expensive and mostly very nasty to work with.

There are two pack versions of various finishes, catalised resins, epoxy resins and other two part products ...... but none of them are perfect and they all have their issues.

There is no free lunch and you can not change the laws of physics.

cheers

Quote:

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Originally Posted by soundman

The whole point of two pack poly is that it is flexible and resilient.

There are other two pack finishes that are hard and clear but much less flexible ..... but there in lies the problem .... because they are less flexible they crack on material with movement
This is why most two pack finished kitchens and the like are made from manufactured board such as MDF.

The thing you gota remember is ...... there IS NO free lunch.

IF the finish is crystal clear and water white, it will be UV suceptable ..... if it does not yellow it will break down otherwise.

There simply is no way to produce UV durability with out introducing colour or opacity at at least some level.

Likewise a high opticly clear finish will by nature be be hard and crystaline in nature..... it's a matter of atomic physics

Look at any lense material ....... The optical clarity will be related in some way to hardness ...... soft plastics will very rarely have the optical performance of even closely related harder plastics.

If you want to introduce strength and durability to a resin, the easiest way to do that is to introduce solids ..... in fact if you are buying opaque paints and glues, you should be looking at the solids content as an indicator of quality.

Here lies the problem with clear finishes, introducing solids to increase durability, increases opacity ......... I know of no case where a clear finish will perform anywhere near as well, ias for durability and UV resistance as an opaque product bassed on the same resin system.

I little observation in plastics will show you that even different colours of exactly the same plastic perform differently .... some colours will be harder some will be more flexible ..... it depends on what has been used to colour the product. ..... different colours will definitely be more durable than others .... this even extends to inks for the same reason ...... Black will pretty much always be the hardest and most UV durable.

Yes there are some compromise products that produce very good results ..... but hell they are expensive and mostly very nasty to work with.

There are two pack versions of various finishes, catalised resins, epoxy resins and other two part products ...... but none of them are perfect and they all have their issues.

There is no free lunch and you can not change the laws of physics.

cheers

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Thanks again Soundman.

I take it these hard & clear 2 pack finishes are the auto lacquers you spray. And that hardwood furniture made solid shouldn't crack with them.

I now see what you mean about Oil Based PolyU looking like plastic & opaque. It became very clear when I buffed an old piece to a high gloss. Interestingly though, it glossed up very shiny. Some comments on various sites say oil based PolyU can't be glossed to a high gloss. Well mine was pretty high, no real visible small scratches left & sharper reflections than straight from can w/brush.

Anyway I'm done with Oil Based PolyU, I will try a 2pack PolyU on a test piece & see how transparent it is, and if thinning it reduces gloss when buffed.

From your previous post:

Quote:

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Originally Posted by soundman

Oh and if ya not thinning ya polly U, and using it straight from the can .... ya making life hard for ya self.

cheers

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For me thinning is only if you intend to cut & polish. I think once you thin, you better off just spraying lacquer.

thanks

There are hard two pack products that are specific to the timber industry.

You must remember all timber has some movement and if crisp hard finishes are used, they may crack.

As for thinning polly ....... serioulsy if you are brushing and not thinning at least 5% you are just making things hard, it will fail to flow off the brush properly and in warmer weather it will go off too fast and maintaining a wet running edge will be difficult.

cheers