more newbie questions

[linnracing]

Hi everybody,
I have the hobby gun and have had fair results. (they would be better if I quit dropping the pieces on the asphalt outside during cooling). I have a couple of questions for those of you moreexperienced. I’m getting what looks like dust or dirt specs in some ares of the finshed pieces. I think I prepped it correctly, sandblasted, blew off with air and wiped off with laquer thinner. Any idea what these specs may be (other than dust specs)?
When I put clear powder over the chrome color I think I baked it to long and to hot. The result was a yellowish brown color in thick areas where it flowed. Can I wet sand this color out and reclear it or do I need to strip the whole part?
Last question, Is there anything I can use for a substitute powder to practice with the gun and fine tune the spray pattern? It seems to come out of the gun really fast.
Thanks in advance for any advice.
Steve

[non-stick]

Glad to see you got "bitten by the bug" and like it.

1) stop dropping things. It does you no good to get that "ground texture" on anything.

2) Make sure you have clean powder and there's nothing flying around like dust and smut in your "work area" and in your oven. A clean shop is a happy shop.

3) sounds a little hot and heavy to me. Try coating a little less and curing for just a smidge less. Usually 15 minutes at 410 PMT is sufficient for most any clear. Try stripping the part and re-coating. If you can get away with sanding it, then lucky you.

4) cut down your air pressure and try different techniques. Gather all of the powdr you sprayed before off of the coating booth floor, give it a rough sifting and play with that stuff. Good practice, that "junk" powder. Unfortunately, the only thing that sprays like plastic for powder coatings is indeed plastic powders for coating. Save some junk powder and give it a whirl. You were just going to throw it out anyways and not to mention.... one can never have enough practice.

Hope some of that helps you. Anybody else have any good advice for our newbie here? Impart your pearls of wisdom, please.

[DALE]

If the powder is coming out way too fast don't fill the cup above half and turn the air pressure way down till you get what you want.As for practice powder other than powder coat don't use anything else. The dust is probably just that but it may be rag lint from the thinner wipe off step.First blow out oven several times to help reduce dust in wet stage.After laquer wipe, blow off again. Yellowing of clear is way too hot I cure clear between 325 and 350F. As for the asphalt damage I can only suggest when part is done turn off oven and crack door open to allow cooling,when totally cooled then you can handle it normally without any heat to deal with. I don't wet sand, I strip and recoat but what ever works for you.After some experience you will get to where you rarely recoat.

[linnracing]

Thanks for the quick reply non-stick and Dale.
Non-stick, you said you bake the clear for 15 min at 410 while Dale does it at 325. Does the powder really have such a wide range of cure times and temp or is this a case of different powder manufactures. Also, how do I know for sure that I have done a quality job? The finsh looks nice on some things I have done but when using the digital temp gun it never quite reached the 400 degree mark when I checked it. (Although I did not want to keep opening the door to recheck it). My guess is that time will tell.
I will try and do a better job of cleaning my work enviorment.
Thanks for all of your help, you guys are awesome.

Steve

[non-stick]

whenever I say a time or temp, it's just a guideline as I don't know what you guys are using. The lower temp may be correct as far as I know. I always speak in terms of " general" to keep the horizons broad, so to speak. That temperature very well may be correct for what you are using. Sorry for the confusion if it created any.

[tomg552001]

Definatly blow off your part after wiping it down to get dust off from the rag. As far as cure, with clears i cure at 375-425 and i never get yellowing or any change in color. This part was done with a high gloss clear at around 400, and as you can see, there is no yellowing.



Good luck, you'll get it.

[DALE]

With my temp suggestion it is mearly my preferrence to cure at lower temps. This is not a guideline. Most all of the powders on the market will flow at 300F with Low temp powders being the exception, I've seen them flow as low as 250F. 400F to 425F to works just fine but in a yellowing of clear or white lowering the temp is usualy a quick fix.Experiment you'll get it--just takes a while to get the feel.

TomG--- looking good as usual

[duke]

hey tom, no more pics. i'll have to knock a wall out so i can scroll across far enough to see them.

cheers