Pasta Machine Leaving Streaks on Polymer Clay? (How to Fix)

Built-up residue on your pasta machine is one of the most annoying things that can happen when working with polymer clay — especially when you are eager to start your next project!

You roll the first sheet of clay through your seemingly sparkling clean machine and bam, there they are: little bits and pieces of previous projects have invaded and destroyed your nice new clean sheet. 

The most common reason why a pasta machine leaves streaks on fresh polymer clay is because there is build-up of old colors in the crevices of the rollers. Streaks can also happen because the pasta machine rollers have developed scratches over time. Properly cleaning the machine and using a paper barrier will help prevent both types.

How do you clean old polymer clay out of a pasta machine?

The part of your pasta machine that the polymer clay passes through is composed of two elements: a roller and a scraper. The clay first curves on the cylinder-shaped roller, then gets scraped down by the scraper and finally comes out through the bottom of your machine. 

Polymer clay residue happens when clay somehow gets stuck behind the scraper and starts building up on the inside part of the roller. This can happen if there is a gap between the two parts or if the scraper has bent over time. 

You may have caused it as well by trying to jam large quantities of very sticky or hard clay through. So to prevent it, ensure your clay is in the proper condition and amount before putting it through. 

If clay residue is already present, you have to simply clean up your machine. Use a test piece of clay prior to running the first sheet to avoid having to scrap clean batches.

Here is how to clean your pasta machine: 

  • First of all, do not try to take it apart unless you are using a really old model that can easily be put back together. Most contemporary machines cannot be. You have to clean them solely from the outside.  
  • Turn your machine around so the smaller of the two fins is facing you. This way you should be able to see better the inside of the rollers and the pieces of old clay that are stuck there. 
  • Scrape the residue away using a bamboo skewer or a plastic knife. Do not use sharp metal objects, for they can damage your rollers. Do not bend the scraper. This will result in possible gaps and more build-up later on because of that. 
  • Shake up the machine a little bit so any left off pieces fall out. Turn it so the bigger fin is facing you and try to clean it from this side the same way. Be aware that you can never clean this side perfectly. But if you do this on a regular basis and you use a test scarp sheet you will successfully get rid of most of the residue. 

Can you stop a pasta machine from leaving grey streaks on polymer clay?

There are generally two types of streaks caused by pasta machines. The first type is the roller lines that you most likely will get on the thickest settings: they are not of any color per se, but cause visible texturing on the sheet. The other type is dark gray or black-colored streaks that appear no matter the settings you are running your clay through.

Lines of the first type occur because in thicker settings the gears of the machine are very far apart, so that only their tips are touching when they turn. You can probably hear a clunking sound that indicates that. 

To prevent it or get rid of existing lines, simply try rolling out your clay in a thinner setting. This way the gears will be closer together and the lines will go away. You can fold your clay in half to get a thicker result despite the thinner setting. 

If you absolutely have to put your clay through the thicker setting(s), make sure you roll it more than once and turn it every time you put it in the machine. After the second or third time the lines will disappear. 

If you are dealing with the colored streaks, once you see them, there is no turning back. However, you can prevent this by not putting thick clay through. Firm brands (like Premo, Cernit or Fimo) will definitely cause black streaks if you run them through your machine without any preparation.

Say you own a standard machine, with sizes from 1 to 9, 9 being the thinnest. If you want your clay sheet to be a 9, do not put a thick piece in and expect it thinning right away. This will only damage your machine.

Instead, roll out the clay into a sheet with a rolling pin first until it is about size 1 and put it through size 1 setting. Gradually continue through the other settings after that until you reach the 9. 

Why do pasta machines leave dark streaks on polymer clay?

The dark streaks that your pasta machine leaves on your polymer clay sheets are most likely due to scratches on its rollers. The pasta machine rollers that you get in craft stores specifically for polymer clay usually are not made of stainless steel but have a thin chrome coating that wears out pretty quickly. 

The scratches occur when your scraper bends over time because of large quantities of firm clay that have been put through it. Its edges start damaging the roller’s surface. The markings most often appear on the sides of the rollers. 

The darkness that you see on your sheet is a chemical reaction called oxidizing. It happens between the metal below the chrome coating where the surface of the roller has been scratched, the clay, and oxygen. 

How do you remove grey or black streaks from polymer clay sheets?

Aside from covering up the discoloration with a thinner sheet of clay, you cannot get dark streaks out once they are printed on your clay. What you can do is prevent them from happening in the first place.

To do that, run a test scrap sheet a couple of times before you start working with your project clay. The streaks will stop to appear eventually and quite some time will be needed for them to start appearing again.  

Should you skip settings when you use a pasta machine to roll out polymer clay?

It is not recommended to skip any setting when rolling out your polymer clay sheets. This will be very hard on your pasta machine, even if the settings do not look so visibly different to you. 

The clay needs to be thinned gradually, otherwise your scraper will gent bent. Of course, if you want to stop at a thicker setting, you do not have to let the clay through the thinner ones. 

What can you use as a barrier between the polymer clay and the pasta machine?

You can always use a physical barrier to put between your pasta machine and your clay sheet to prevent any ripples, dark streaks or traces of old clay appearing. 

The best material for that is paper. You can use a sheet of regular printing paper, wax, parchment or greaseproof paper. 

Place one sheet on either side of the clay, or folded in half so that it covers both sides of the clay. Change and turn around the sheets regularly to avoid your clay from getting dirty of the residue on them.  

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