New Boy and spraying query

[Alan Smith]

Hi, I'd like to introduce myself to this forum. I'm a semi-pro furniture designer/maker (woodworking is my second career) I'm involved with the process right from the start in that I grow and mill my own timber. Most of my work load at the moment is built ins/fitting and trim with not as much one off items of furniture as I would like but I'm getting there.

My query today concerns the use of Osmo Polyx which is my favourite finish. I've used this for years and am more then pleased with results. However my workload now is such that I would like to speed up the process and have been experimenting with spraying. Now I will admit right at the start I know the square root of B -all about spraying. I was wondering if anyone could give some pointers ar share experiences re spraying this particular finish. Particularly with regard to setting up the spray gun and safety issues re fume extraction etc.

What I have equipment wise is a 3Hp compressor with 100 litre tank. The gun I picked up at the local second hand tool shop for a few quid is a Binks 222 with 0.060 nozzle. I've had best success using the PolyX straight out of the can with a fairly high pressure ? 2.5Bar I think. I apply and then wipe down just as if applying with brush or sponge. results seem to be good but would really like to know a little more about this spraying game.

Look forward to any replies.

Thanks,

Alan

 

[DaveL]

Hi Alan,

Welcome to the forum.

That is a good first post, not many people have the time or space to grow their own timber, green, who me? :mrgreen:

I can't help with the spraying but there are a some members who do it on a regular basis, I am sure help with appear.

 

[davy_owen_88]

I can't offer advice on spraying that particular finish, nor can I find any info on that particular spray gun but here are a few pointers on general spraying (I spray guitars so some of this might be irrelevent:

- Use the lowest pressure you can to atomise the finish. I.e, for it to come out as a spray not just a series of blobs. If you see orange peel then you need more pressure.
- A number of thinner coats is better than one thick coat.
- Always allow time for solvents to rise before spraying the next coat.
- For the final coat, thinning it down will allow for better flow-out and therefore a better finish that requires less flattening.
- I spray at about 35-45psi depending on how much I have thinned the finish.
- Hold the gun about 6-8 inches away, and parallel with, the work piece - don't swing your arm.
- Make sure you are wearing a good quality respirator with suitable filters - charcoal filters if the finish has a strong odour.
- If you are spraying anywhere drafty then goggles and a full spray/chemical suit is a good idea so that any over-spray doesn't get blown back over you.
- Effective fume extraction requires very high air flow rates but having airflow blowing into the booth helps to prevent the vapours from escaping which gives the extractor a bit more time.
- A large, disposable, absorbent cloth placed behind the object being sprayed is useful for catching some over-spray.

Most guns come with controls for fluid and air. As you increase the fluid output you'll need to increase the pressure a bit. The air control alters the shape of the spray. A wider pattern requires a higher pressure and you'll also need to increase fluid delivery. There might also be a rotating cap at the nozzle of the gun, this controls the direction the air pushes the finish - if the air is blowing from the sides you will get a vertical spray pattern and vice versa.

That's about all I can think of off the top of my head, but if you can give some more info regarding the spray gun then I might be able to offer some more tips. Also if you have any specific questions then ask away.

I'm sure there are other users who have experience with that gun/finish so they might be along soon to offer their advice.


EDIT:

After all that I remembered about a website that I found extremely useful when I started spraying...

http://www.stewmac.com/freeinfo/I-5436.html

 

[Alan Smith]

Thanks guys, that Stewmac site has pretty much everything I need to know about setting up sprayguns.

 

[johnnyb]

what type of finish is osmo. is it an oil? if it is the only advantage would be speed of application. simply apply a wet coat all over(use a quite low pressure) allow to stand then remove excess.

 

[Philly]

Welcome aboard, Alan!
Philly

 

[Alan Smith]

Johnnyb,

Osmo produce a range of what they describe as hardwax finishes. It's basically a liquid wax with I presume some sophisticated driers/hardeners. As I alluded above I've used it for years. It has lots of useful properties not least, very low toxicity, so suitable for use on wooden toys and kitchen implements. Also good water resistant properties, I have a wooden shower cubicle at home treated with this. It's about 10 years old now, mostly T+G softwood but not showing any staining or distress.

You are right, my aim in spraying is purely speed of application. Spray on, leave then wipe off excess. So I'm not too concerned about good quality of sprayed finish, only delivery of an economically metered amount.